code: def _removeHeaderTag(header, tag):
      
      if header.startswith(tag):
          tagPresent = True
          header = header[len(tag):]
      else:
          tagPresent = False
      return header, tagPresent
docs: Removes a tag from the beginning of a header string.
  
      :param header: str
      :param tag: str
      :returns: (str, bool), header without the tag and a bool that indicates
          wheter the tag was present.