public function pushProcessor($callback)
    {
        if (!is_callable($callback)) {
            throw new \InvalidArgumentException('Processors must be valid callables (callback or object with an __invoke method), '.var_export($callback, true).' given');
        }
        array_unshift($this->processors, $callback);

        return $this;
    }
public function pushProcessor($callback)
    {
        if (!is_callable($callback)) {
            throw new \InvalidArgumentException('Processors must be valid callables (callback or object with an __invoke method), '.var_export($callback, true).' given');
        }
        array_unshift($this->processors, $callback);

        return $this;
    }
public function pushProcessor ( $ callback ) { if ( ! is_callable ( $ callback ) ) { throw new \ InvalidArgumentException ( 'Processors must be valid callables (callback or object with an __invoke method), ' . var_export ( $ callback , true ) . ' given' ) ; } array_unshift ( $ this -> processors , $ callback ) ; return $ this ; }
Adds a processor on to the stack.

@param  callable $callback
@return $this
Adds a processor on to the stack .