[[1]:[2]]
-----
Groovy script
  Generalized list
    PsiElement([)('[')
    Named argument
      Argument label
        Generalized list
          PsiElement([)('[')
          Literal
            PsiElement(Integer)('1')
          PsiElement(])(']')
      PsiElement(:)(':')
      Generalized list
        PsiElement([)('[')
        Literal
          PsiElement(Integer)('2')
        PsiElement(])(']')
    PsiElement(])(']')