code: def _check_accept_keywords(approved, flag):
      '''check compatibility of accept_keywords'''
      if flag in approved:
          return False
      elif (flag.startswith('~') and flag[1:] in approved) \
              or ('~'+flag in approved):
          return False
      else:
          return Truf _check_accept_keywords(approved, flag):
      '''check compatibility of accept_keywords'''
      if flag in approved:
          return False
      elif (flag.startswith('~') and flag[1:] in approved) \
              or ('~'+flag in approved):
          return False
      else:
          return True
docs: check compatibility of accept_keywords