code: def check_docstring_first(src, filename='<unknown>'):
      # type: (bytes, str) -> int
      
      found_docstring_line = None
      found_code_line = None
  
      tok_gen = tokenize_tokenize(io.BytesIO(src).readline)
      for tok_type, _, (sline, scol), _, _ in tok_gen:
          # Looks like a docstring!
          if tok_type == tokenize.STRING and scol == 0:
              if found_docstring_line is not None:
                  print(
                      '{}:{} Multiple module docstrings '
                      '(first docstring on line {}).'.format(
                          filename, sline, found_docstring_line,
                      ),
                  )
                  return 1
              elif found_code_line is not None:
                  print(
                      '{}:{} Module docstring appears after code '
                      '(code seen on line {}).'.format(
                          filename, sline, found_code_line,
                      ),
                  )
                  return 1
              else:
                  found_docstring_line = sline
          elif tok_type not in NON_CODE_TOKENS and found_code_line is None:
              found_code_line = sline
  
      return 0
docs: Returns nonzero if the source has what looks like a docstring that is
      not at the beginning of the source.
  
      A string will be considered a docstring if it is a STRING token with a
      col offset of 0.