public function addHandler($operation, callable $callback)
    {
        $this->handlers[$operation] = $callback;
        $this->addOperation($operation);
    }
public function addHandler($operation, callable $callback)
    {
        $this->handlers[$operation] = $callback;
        $this->addOperation($operation);
    }
public function addHandler ( $ operation , callable $ callback ) { $ this -> handlers [ $ operation ] = $ callback ; $ this -> addOperation ( $ operation ) ; }
Adds a handler AND operation for the named operation.

@param string   $operation
@param callable $callback
Adds a handler AND operation for the named operation .