docs: def check_string(sql_string, add_semicolon=False):
      """
      Check whether a string is valid PostgreSQL. Returns a boolean
      indicating validity and a message from ecpg, which will be an
      empty string if the input was valid, or a description of the
      problem otherwise.
      """
      prepped_sql = sqlprep.prepare_sql(sql_string, add_semicolon=add_semicolon)
      success, msg = ecpg.check_syntax(prepped_sql)
      return success, msg