is_callable

<?php                 $this->ensureBinDirIsInPath();



                if (!is_string($callable)) {

                    if (!is_callable($callable)) {

                        $className = is_object($callable[0]) ? get_class($callable[0]) : $callable[0];



                        throw new \RuntimeException('Subscriber '.$className.'::'.$callable[1].' for event '.$event->getName().' is not callable, make sure the function is defined and public');

<?php                         $this->io->writeError('<warning>Class '.$className.' is not autoloadable, can not call '.$event->getName().' script</warning>', true, IOInterface::QUIET);

                        continue;

                    }

                    if (!is_callable($callable)) {

                        $this->io->writeError('<warning>Method '.$callable.' is not callable, can not call '.$event->getName().' script</warning>', true, IOInterface::QUIET);

                        continue;

                    }

<?php             }

        }



        $callback = is_callable($output) ? $output : array($this, 'outputHandler');

        $process->run($callback);



        if ($this->captureOutput && !is_callable($output)) {

<?php         $callback = is_callable($output) ? $output : array($this, 'outputHandler');

        $process->run($callback);



        if ($this->captureOutput && !is_callable($output)) {

            $output = $process->getOutput();

        }

<?php                 $ret = null;

                if (isset($this->configValueMap[$arg])) {

                    $ret = $this->configValueMap[$arg];

                    if (is_callable($ret)) {

                        $ret = $ret();

                    }

                }

<?php         $this->captureOutput = func_num_args() > 3;

        $this->errorOutput = '';



        $callback = is_callable($output) ? $output : array($this, 'outputHandler');



        $this->log[] = $command;

<?php             call_user_func($callback, Process::ERR, $stderr);

        }



        if ($this->captureOutput && !is_callable($output)) {

            $output = $stdout;

        }