code: def get_comment(value):
      
      if value and value[0] != '(':
          raise errors.HeaderParseError(
              "expected '(' but found '{}'".format(value))
      comment = Comment()
      value = value[1:]
      while value and value[0] != ")":
          if value[0] in WSP:
              token, value = get_fws(value)
          elif value[0] == '(':
              token, value = get_comment(value)
          else:
              token, value = get_qp_ctext(value)
          comment.append(token)
      if not value:
          comment.defects.append(errors.InvalidHeaderDefect(
              "end of header inside comment"))
          return comment, value
      return comment, value[1:]
docs: comment = "(" *([FWS] ccontent) [FWS] ")"
         ccontent = ctext / quoted-pair / comment
  
      We handle nested comments here, and quoted-pair in our qp-ctext routine.