Add a comment for fastboot. (#798)
diff --git a/mobly/controllers/android_device.py b/mobly/controllers/android_device.py
index 843d8eb..f9de311 100644
--- a/mobly/controllers/android_device.py
+++ b/mobly/controllers/android_device.py
@@ -242,6 +242,9 @@
"""List all android devices connected to the computer that are in in
fastboot mode. These are detected by fastboot.
+ This function doesn't raise any error if `fastboot` binary doesn't exist,
+ because `FastbootProxy` itself doesn't raise any error.
+
Returns:
A list of android device serials. Empty if there's none.
"""
