private void commandShowFunctions(CliCommand command) throws ExecutorException {
    List<SqlFunction> fns = executor.listFunctions(exeContext);
    for (SqlFunction fn : fns) {
      writer.println(fn.toString());
    }
    writer.flush();
  }
Handles the given command
@param command input {@link CliCommand} to handle
@return false if command is to quit, or fatal error happened that Shell should not continue running. True o.w.
@throws CommandHandlerException if unrecoverable error happened while handling the input {@link CliCommand}
samza-sql-shell/src/main/java/org/apache/samza/sql/client/impl/CliCommandHandler.java