Grammar/Grammar - platform/external/python/cpython3 - Git at Google

 # Grammar for Python

 # NOTE WELL: You should also follow all the steps listed at
 # https://devguide.python.org/grammar/

 # Start symbols for the grammar:
 #       single_input is a single interactive statement;
 #       file_input is a module or sequence of commands read from an input file;
 #       eval_input is the input for the eval() functions.
 #       func_type_input is a PEP 484 Python 2 function type comment
 # NB: compound_stmt in single_input is followed by extra NEWLINE!
 # NB: due to the way TYPE_COMMENT is tokenized it will always be followed by a NEWLINE
 single_input: NEWLINE | simple_stmt | compound_stmt NEWLINE
 file_input: (NEWLINE | stmt)* ENDMARKER
 eval_input: testlist NEWLINE* ENDMARKER

 decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
 decorators: decorator+
 decorated: decorators (classdef | funcdef | async_funcdef)

 async_funcdef: ASYNC funcdef
 funcdef: 'def' NAME parameters ['->' test] ':' [TYPE_COMMENT] func_body_suite

 parameters: '(' [typedargslist] ')'

 # The following definition for typedarglist is equivalent to this set of rules:
 #
 #     arguments = argument (',' [TYPE_COMMENT] argument)*
 #     argument = tfpdef ['=' test]
 #     kwargs = '**' tfpdef [','] [TYPE_COMMENT]
 #     args = '*' [tfpdef]
 #     kwonly_kwargs = (',' [TYPE_COMMENT] argument)* (TYPE_COMMENT | [',' [TYPE_COMMENT] [kwargs]])
 #     args_kwonly_kwargs = args kwonly_kwargs | kwargs
 #     poskeyword_args_kwonly_kwargs = arguments ( TYPE_COMMENT | [',' [TYPE_COMMENT] [args_kwonly_kwargs]])
 #     typedargslist_no_posonly  = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs
 #     typedarglist = (arguments ',' [TYPE_COMMENT] '/' [',' [[TYPE_COMMENT] typedargslist_no_posonly]])|(typedargslist_no_posonly)"
 #
 # It needs to be fully expanded to allow our LL(1) parser to work on it.

 typedargslist: (
   (tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* ',' [TYPE_COMMENT] '/' [',' [ [TYPE_COMMENT] tfpdef ['=' test] (
         ',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [
         '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
       | '**' tfpdef [','] [TYPE_COMMENT]]])
   | '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
   | '**' tfpdef [','] [TYPE_COMMENT]]] )
 |  (tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] [
    '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
   | '**' tfpdef [','] [TYPE_COMMENT]]])
   | '*' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT | [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
   | '**' tfpdef [','] [TYPE_COMMENT])
 )
 tfpdef: NAME [':' test]

 # The following definition for varargslist is equivalent to this set of rules:
 #
 #     arguments = argument (',' argument )*
 #     argument = vfpdef ['=' test]
 #     kwargs = '**' vfpdef [',']
 #     args = '*' [vfpdef]
 #     kwonly_kwargs = (',' argument )* [',' [kwargs]]
 #     args_kwonly_kwargs = args kwonly_kwargs | kwargs
 #     poskeyword_args_kwonly_kwargs = arguments [',' [args_kwonly_kwargs]]
 #     vararglist_no_posonly = poskeyword_args_kwonly_kwargs | args_kwonly_kwargs
 #     varargslist = arguments ',' '/' [','[(vararglist_no_posonly)]] | (vararglist_no_posonly)
 #
 # It needs to be fully expanded to allow our LL(1) parser to work on it.

 varargslist: vfpdef ['=' test ](',' vfpdef ['=' test])* ',' '/' [',' [ (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
         '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
       | '**' vfpdef [',']]]
   | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
   | '**' vfpdef [',']) ]] | (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
         '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
       | '**' vfpdef [',']]]
   | '*' [vfpdef] (',' vfpdef ['=' test])* [',' ['**' vfpdef [',']]]
   | '**' vfpdef [',']
 )
 vfpdef: NAME

 stmt: simple_stmt | compound_stmt
 simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
 small_stmt: (expr_stmt | del_stmt | pass_stmt | flow_stmt |
              import_stmt | global_stmt | nonlocal_stmt | assert_stmt)
 expr_stmt: testlist_star_expr (annassign | augassign (yield_expr|testlist) |
                      [('=' (yield_expr|testlist_star_expr))+ [TYPE_COMMENT]] )
 annassign: ':' test ['=' (yield_expr|testlist_star_expr)]
 testlist_star_expr: (test|star_expr) (',' (test|star_expr))* [',']
 augassign: ('+=' | '-=' | '*=' | '@=' | '/=' | '%=' | '&=' | '|=' | '^=' |
             '<<=' | '>>=' | '**=' | '//=')
 # For normal and annotated assignments, additional restrictions enforced by the interpreter
 del_stmt: 'del' exprlist
 pass_stmt: 'pass'
 flow_stmt: break_stmt | continue_stmt | return_stmt | raise_stmt | yield_stmt
 break_stmt: 'break'
 continue_stmt: 'continue'
 return_stmt: 'return' [testlist_star_expr]
 yield_stmt: yield_expr
 raise_stmt: 'raise' [test ['from' test]]
 import_stmt: import_name | import_from
 import_name: 'import' dotted_as_names
 # note below: the ('.' | '...') is necessary because '...' is tokenized as ELLIPSIS
 import_from: ('from' (('.' | '...')* dotted_name | ('.' | '...')+)
               'import' ('*' | '(' import_as_names ')' | import_as_names))
 import_as_name: NAME ['as' NAME]
 dotted_as_name: dotted_name ['as' NAME]
 import_as_names: import_as_name (',' import_as_name)* [',']
 dotted_as_names: dotted_as_name (',' dotted_as_name)*
 dotted_name: NAME ('.' NAME)*
 global_stmt: 'global' NAME (',' NAME)*
 nonlocal_stmt: 'nonlocal' NAME (',' NAME)*
 assert_stmt: 'assert' test [',' test]

 compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt
 async_stmt: ASYNC (funcdef | with_stmt | for_stmt)
 if_stmt: 'if' namedexpr_test ':' suite ('elif' namedexpr_test ':' suite)* ['else' ':' suite]
 while_stmt: 'while' namedexpr_test ':' suite ['else' ':' suite]
 for_stmt: 'for' exprlist 'in' testlist ':' [TYPE_COMMENT] suite ['else' ':' suite]
 try_stmt: ('try' ':' suite
            ((except_clause ':' suite)+
             ['else' ':' suite]
             ['finally' ':' suite] |
            'finally' ':' suite))
 with_stmt: 'with' with_item (',' with_item)*  ':' [TYPE_COMMENT] suite
 with_item: test ['as' expr]
 # NB compile.c makes sure that the default except clause is last
 except_clause: 'except' [test ['as' NAME]]
 suite: simple_stmt | NEWLINE INDENT stmt+ DEDENT

 namedexpr_test: test [':=' test]
 test: or_test ['if' or_test 'else' test] | lambdef
 test_nocond: or_test | lambdef_nocond
 lambdef: 'lambda' [varargslist] ':' test
 lambdef_nocond: 'lambda' [varargslist] ':' test_nocond
 or_test: and_test ('or' and_test)*
 and_test: not_test ('and' not_test)*
 not_test: 'not' not_test | comparison
 comparison: expr (comp_op expr)*
 # <> isn't actually a valid comparison operator in Python. It's here for the
 # sake of a __future__ import described in PEP 401 (which really works :-)
 comp_op: '<'|'>'|'=='|'>='|'<='|'<>'|'!='|'in'|'not' 'in'|'is'|'is' 'not'
 star_expr: '*' expr
 expr: xor_expr ('|' xor_expr)*
 xor_expr: and_expr ('^' and_expr)*
 and_expr: shift_expr ('&' shift_expr)*
 shift_expr: arith_expr (('<<'|'>>') arith_expr)*
 arith_expr: term (('+'|'-') term)*
 term: factor (('*'|'@'|'/'|'%'|'//') factor)*
 factor: ('+'|'-'|'~') factor | power
 power: atom_expr ['**' factor]
 atom_expr: [AWAIT] atom trailer*
 atom: ('(' [yield_expr|testlist_comp] ')' |
        '[' [testlist_comp] ']' |
        '{' [dictorsetmaker] '}' |
        NAME | NUMBER | STRING+ | '...' | 'None' | 'True' | 'False')
 testlist_comp: (namedexpr_test|star_expr) ( comp_for | (',' (namedexpr_test|star_expr))* [','] )
 trailer: '(' [arglist] ')' | '[' subscriptlist ']' | '.' NAME
 subscriptlist: subscript (',' subscript)* [',']
 subscript: test | [test] ':' [test] [sliceop]
 sliceop: ':' [test]
 exprlist: (expr|star_expr) (',' (expr|star_expr))* [',']
 testlist: test (',' test)* [',']
 dictorsetmaker: ( ((test ':' test | '**' expr)
                    (comp_for | (',' (test ':' test | '**' expr))* [','])) |
                   ((test | star_expr)
                    (comp_for | (',' (test | star_expr))* [','])) )

 classdef: 'class' NAME ['(' [arglist] ')'] ':' suite

 arglist: argument (',' argument)*  [',']

 # The reason that keywords are test nodes instead of NAME is that using NAME
 # results in an ambiguity. ast.c makes sure it's a NAME.
 # "test '=' test" is really "keyword '=' test", but we have no such token.
 # These need to be in a single rule to avoid grammar that is ambiguous
 # to our LL(1) parser. Even though 'test' includes '*expr' in star_expr,
 # we explicitly match '*' here, too, to give it proper precedence.
 # Illegal combinations and orderings are blocked in ast.c:
 # multiple (test comp_for) arguments are blocked; keyword unpackings
 # that precede iterable unpackings are blocked; etc.
 argument: ( test [comp_for] |
             test ':=' test |
             test '=' test |
             '**' test |
             '*' test )

 comp_iter: comp_for | comp_if
 sync_comp_for: 'for' exprlist 'in' or_test [comp_iter]
 comp_for: [ASYNC] sync_comp_for
 comp_if: 'if' test_nocond [comp_iter]

 # not used in grammar, but may appear in "node" passed from Parser to Compiler
 encoding_decl: NAME

 yield_expr: 'yield' [yield_arg]
 yield_arg: 'from' test | testlist_star_expr

 # the TYPE_COMMENT in suites is only parsed for funcdefs,
 # but can't go elsewhere due to ambiguity
 func_body_suite: simple_stmt | NEWLINE [TYPE_COMMENT NEWLINE] INDENT stmt+ DEDENT

 func_type_input: func_type NEWLINE* ENDMARKER
 func_type: '(' [typelist] ')' '->' test
 # typelist is a modified typedargslist (see above)
 typelist: (test (',' test)* [','
        ['*' [test] (',' test)* [',' '**' test] | '**' test]]
      |  '*' [test] (',' test)* [',' '**' test] | '**' test)
	# Grammar for Python

	# NOTE WELL: You should also follow all the steps listed at
	# https://devguide.python.org/grammar/

	# Start symbols for the grammar:
	# single_input is a single interactive statement;
	# file_input is a module or sequence of commands read from an input file;
	# eval_input is the input for the eval() functions.
	# func_type_input is a PEP 484 Python 2 function type comment
	# NB: compound_stmt in single_input is followed by extra NEWLINE!
	# NB: due to the way TYPE_COMMENT is tokenized it will always be followed by a NEWLINE
	single_input: NEWLINE \| simple_stmt \| compound_stmt NEWLINE
	file_input: (NEWLINE \| stmt)* ENDMARKER
	eval_input: testlist NEWLINE* ENDMARKER

	decorator: '@' dotted_name [ '(' [arglist] ')' ] NEWLINE
	decorators: decorator+
	decorated: decorators (classdef \| funcdef \| async_funcdef)

	async_funcdef: ASYNC funcdef
	funcdef: 'def' NAME parameters ['->' test] ':' [TYPE_COMMENT] func_body_suite

	parameters: '(' [typedargslist] ')'

	# The following definition for typedarglist is equivalent to this set of rules:
	#
	# arguments = argument (',' [TYPE_COMMENT] argument)*
	# argument = tfpdef ['=' test]
	# kwargs = '**' tfpdef [','] [TYPE_COMMENT]
	# args = '*' [tfpdef]
	# kwonly_kwargs = (',' [TYPE_COMMENT] argument)* (TYPE_COMMENT \| [',' [TYPE_COMMENT] [kwargs]])
	# args_kwonly_kwargs = args kwonly_kwargs \| kwargs
	# poskeyword_args_kwonly_kwargs = arguments ( TYPE_COMMENT \| [',' [TYPE_COMMENT] [args_kwonly_kwargs]])
	# typedargslist_no_posonly = poskeyword_args_kwonly_kwargs \| args_kwonly_kwargs
	# typedarglist = (arguments ',' [TYPE_COMMENT] '/' [',' [[TYPE_COMMENT] typedargslist_no_posonly]])\|(typedargslist_no_posonly)"
	#
	# It needs to be fully expanded to allow our LL(1) parser to work on it.

	typedargslist: (
	(tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* ',' [TYPE_COMMENT] '/' [',' [ [TYPE_COMMENT] tfpdef ['=' test] (
	',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT \| [',' [TYPE_COMMENT] [
	'' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test]) (TYPE_COMMENT \| [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
	\| '**' tfpdef [','] [TYPE_COMMENT]]])
	\| '' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test]) (TYPE_COMMENT \| [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
	\| '**' tfpdef [','] [TYPE_COMMENT]]] )
	\| (tfpdef ['=' test] (',' [TYPE_COMMENT] tfpdef ['=' test])* (TYPE_COMMENT \| [',' [TYPE_COMMENT] [
	'' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test]) (TYPE_COMMENT \| [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
	\| '**' tfpdef [','] [TYPE_COMMENT]]])
	\| '' [tfpdef] (',' [TYPE_COMMENT] tfpdef ['=' test]) (TYPE_COMMENT \| [',' [TYPE_COMMENT] ['**' tfpdef [','] [TYPE_COMMENT]]])
	\| '**' tfpdef [','] [TYPE_COMMENT])
	)
	tfpdef: NAME [':' test]

	# The following definition for varargslist is equivalent to this set of rules:
	#
	# arguments = argument (',' argument )*
	# argument = vfpdef ['=' test]
	# kwargs = '**' vfpdef [',']
	# args = '*' [vfpdef]
	# kwonly_kwargs = (',' argument )* [',' [kwargs]]
	# args_kwonly_kwargs = args kwonly_kwargs \| kwargs
	# poskeyword_args_kwonly_kwargs = arguments [',' [args_kwonly_kwargs]]
	# vararglist_no_posonly = poskeyword_args_kwonly_kwargs \| args_kwonly_kwargs
	# varargslist = arguments ',' '/' [','[(vararglist_no_posonly)]] \| (vararglist_no_posonly)
	#
	# It needs to be fully expanded to allow our LL(1) parser to work on it.

	varargslist: vfpdef ['=' test ](',' vfpdef ['=' test])* ',' '/' [',' [ (vfpdef ['=' test] (',' vfpdef ['=' test])* [',' [
	'' [vfpdef] (',' vfpdef ['=' test]) [',' ['**' vfpdef [',']]]
	\| '**' vfpdef [',']]]
	\| '' [vfpdef] (',' vfpdef ['=' test]) [',' ['**' vfpdef [',']]]
	\| '*' vfpdef [',']) ]] \| (vfpdef ['=' test] (',' vfpdef ['=' test]) [',' [
	'' [vfpdef] (',' vfpdef ['=' test]) [',' ['**' vfpdef [',']]]
	\| '**' vfpdef [',']]]
	\| '' [vfpdef] (',' vfpdef ['=' test]) [',' ['**' vfpdef [',']]]
	\| '**' vfpdef [',']
	)
	vfpdef: NAME

	stmt: simple_stmt \| compound_stmt
	simple_stmt: small_stmt (';' small_stmt)* [';'] NEWLINE
	small_stmt: (expr_stmt \| del_stmt \| pass_stmt \| flow_stmt \|
	import_stmt \| global_stmt \| nonlocal_stmt \| assert_stmt)
	expr_stmt: testlist_star_expr (annassign \| augassign (yield_expr\|testlist) \|
	[('=' (yield_expr\|testlist_star_expr))+ [TYPE_COMMENT]] )
	annassign: ':' test ['=' (yield_expr\|testlist_star_expr)]
	testlist_star_expr: (test\|star_expr) (',' (test\|star_expr))* [',']
	augassign: ('+=' \| '-=' \| '*=' \| '@=' \| '/=' \| '%=' \| '&=' \| '\|=' \| '^=' \|
	'<<=' \| '>>=' \| '**=' \| '//=')
	# For normal and annotated assignments, additional restrictions enforced by the interpreter
	del_stmt: 'del' exprlist
	pass_stmt: 'pass'
	flow_stmt: break_stmt \| continue_stmt \| return_stmt \| raise_stmt \| yield_stmt
	break_stmt: 'break'
	continue_stmt: 'continue'
	return_stmt: 'return' [testlist_star_expr]
	yield_stmt: yield_expr
	raise_stmt: 'raise' [test ['from' test]]
	import_stmt: import_name \| import_from
	import_name: 'import' dotted_as_names
	# note below: the ('.' \| '...') is necessary because '...' is tokenized as ELLIPSIS
	import_from: ('from' (('.' \| '...')* dotted_name \| ('.' \| '...')+)
	'import' ('*' \| '(' import_as_names ')' \| import_as_names))
	import_as_name: NAME ['as' NAME]
	dotted_as_name: dotted_name ['as' NAME]
	import_as_names: import_as_name (',' import_as_name)* [',']
	dotted_as_names: dotted_as_name (',' dotted_as_name)*
	dotted_name: NAME ('.' NAME)*
	global_stmt: 'global' NAME (',' NAME)*
	nonlocal_stmt: 'nonlocal' NAME (',' NAME)*
	assert_stmt: 'assert' test [',' test]

	compound_stmt: if_stmt \| while_stmt \| for_stmt \| try_stmt \| with_stmt \| funcdef \| classdef \| decorated \| async_stmt
	async_stmt: ASYNC (funcdef \| with_stmt \| for_stmt)
	if_stmt: 'if' namedexpr_test ':' suite ('elif' namedexpr_test ':' suite)* ['else' ':' suite]
	while_stmt: 'while' namedexpr_test ':' suite ['else' ':' suite]
	for_stmt: 'for' exprlist 'in' testlist ':' [TYPE_COMMENT] suite ['else' ':' suite]
	try_stmt: ('try' ':' suite
	((except_clause ':' suite)+
	['else' ':' suite]
	['finally' ':' suite] \|
	'finally' ':' suite))
	with_stmt: 'with' with_item (',' with_item)* ':' [TYPE_COMMENT] suite
	with_item: test ['as' expr]
	# NB compile.c makes sure that the default except clause is last
	except_clause: 'except' [test ['as' NAME]]
	suite: simple_stmt \| NEWLINE INDENT stmt+ DEDENT

	namedexpr_test: test [':=' test]
	test: or_test ['if' or_test 'else' test] \| lambdef
	test_nocond: or_test \| lambdef_nocond
	lambdef: 'lambda' [varargslist] ':' test
	lambdef_nocond: 'lambda' [varargslist] ':' test_nocond
	or_test: and_test ('or' and_test)*
	and_test: not_test ('and' not_test)*
	not_test: 'not' not_test \| comparison
	comparison: expr (comp_op expr)*
	# <> isn't actually a valid comparison operator in Python. It's here for the
	# sake of a __future__ import described in PEP 401 (which really works :-)
	comp_op: '<'\|'>'\|'=='\|'>='\|'<='\|'<>'\|'!='\|'in'\|'not' 'in'\|'is'\|'is' 'not'
	star_expr: '*' expr
	expr: xor_expr ('\|' xor_expr)*
	xor_expr: and_expr ('^' and_expr)*
	and_expr: shift_expr ('&' shift_expr)*
	shift_expr: arith_expr (('<<'\|'>>') arith_expr)*
	arith_expr: term (('+'\|'-') term)*
	term: factor ((''\|'@'\|'/'\|'%'\|'//') factor)
	factor: ('+'\|'-'\|'~') factor \| power
	power: atom_expr ['**' factor]
	atom_expr: [AWAIT] atom trailer*
	atom: ('(' [yield_expr\|testlist_comp] ')' \|
	'[' [testlist_comp] ']' \|
	'{' [dictorsetmaker] '}' \|
	NAME \| NUMBER \| STRING+ \| '...' \| 'None' \| 'True' \| 'False')
	testlist_comp: (namedexpr_test\|star_expr) ( comp_for \| (',' (namedexpr_test\|star_expr))* [','] )
	trailer: '(' [arglist] ')' \| '[' subscriptlist ']' \| '.' NAME
	subscriptlist: subscript (',' subscript)* [',']
	subscript: test \| [test] ':' [test] [sliceop]
	sliceop: ':' [test]
	exprlist: (expr\|star_expr) (',' (expr\|star_expr))* [',']
	testlist: test (',' test)* [',']
	dictorsetmaker: ( ((test ':' test \| '**' expr)
	(comp_for \| (',' (test ':' test \| '*' expr)) [','])) \|
	((test \| star_expr)
	(comp_for \| (',' (test \| star_expr))* [','])) )

	classdef: 'class' NAME ['(' [arglist] ')'] ':' suite

	arglist: argument (',' argument)* [',']

	# The reason that keywords are test nodes instead of NAME is that using NAME
	# results in an ambiguity. ast.c makes sure it's a NAME.
	# "test '=' test" is really "keyword '=' test", but we have no such token.
	# These need to be in a single rule to avoid grammar that is ambiguous
	# to our LL(1) parser. Even though 'test' includes '*expr' in star_expr,
	# we explicitly match '*' here, too, to give it proper precedence.
	# Illegal combinations and orderings are blocked in ast.c:
	# multiple (test comp_for) arguments are blocked; keyword unpackings
	# that precede iterable unpackings are blocked; etc.
	argument: ( test [comp_for] \|
	test ':=' test \|
	test '=' test \|
	'**' test \|
	'*' test )

	comp_iter: comp_for \| comp_if
	sync_comp_for: 'for' exprlist 'in' or_test [comp_iter]
	comp_for: [ASYNC] sync_comp_for
	comp_if: 'if' test_nocond [comp_iter]

	# not used in grammar, but may appear in "node" passed from Parser to Compiler
	encoding_decl: NAME

	yield_expr: 'yield' [yield_arg]
	yield_arg: 'from' test \| testlist_star_expr

	# the TYPE_COMMENT in suites is only parsed for funcdefs,
	# but can't go elsewhere due to ambiguity
	func_body_suite: simple_stmt \| NEWLINE [TYPE_COMMENT NEWLINE] INDENT stmt+ DEDENT

	func_type_input: func_type NEWLINE* ENDMARKER
	func_type: '(' [typelist] ')' '->' test
	# typelist is a modified typedargslist (see above)
	typelist: (test (',' test)* [','
	['' [test] (',' test) [',' '' test] \| '' test]]
	\| '' [test] (',' test) [',' '' test] \| '' test)