code: def _is_mwtab(string):
          
          if isinstance(string, str):
              lines = string.split("\n")
          elif isinstance(string, bytes):
              lines = string.decode("utf-8").split("\n")
          else:
              raise TypeError("Expecting <class 'str'> or <class 'bytes'>, but {} was passed".format(type(string)))
  
          lines = [line for line in lines if line]
          header = lines[0]
  
          if header.startswith("#METABOLOMICS WORKBENCH"):
              return "\n".join(lines)
          return False
docs: Test if input string is in `mwtab` format.
  
          :param string: Input string.
          :type string: :py:class:`str` or :py:class:`bytes`
          :return: Input string if in mwTab format or False otherwise.
          :rtype: :py:class:`str` or :py:obj:`False`