src/WorkerF/Tool/Pipeline.php
public function pipe($pipe) 
    {
        if (FALSE === is_callable($pipe)) {
            throw new InvalidArgumentException('pipe should be callable.');
        }

        $this->_pipes[] = $pipe;

        return $this;
    }
public function pipe($pipe) 
    {
        if (FALSE === is_callable($pipe)) {
            throw new InvalidArgumentException('pipe should be callable.');
        }

        $this->_pipes[] = $pipe;

        return $this;
    }
set pipes, single mode.

@param $pipe
@return self
@throws \InvalidArgumentException