Environment

• Hardware Environment(Ascend/GPU/CPU):

Uncomment only one /device <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/device ascend
/device gpu
/device cpu

• Software Environment:
  -- MindSpore version (source or binary):
  -- Python version (e.g., Python 3.7.5):
  -- OS platform and distribution (e.g., Linux Ubuntu 16.04):
  -- GCC/Compiler version (if compiled from source):

Related testcase

Steps to reproduce the issue

Describe the current behavior

the comment of step_begin() is wrong.

Describe the expected behavior

It should be 'Called before each step beginning' .

Related log / screenshot

Special notes for this issue