src/Task.php
public function failed($fail = true)
    {
        if (!func_num_args()) {
            return $this->_failed;
        }
        $this->_failed = $fail;
        return $this;
    }
public function failed($fail = true)
    {
        if (!func_num_args()) {
            return $this->_failed;
        }
        $this->_failed = $fail;
        return $this;
    }
Indicates whether the task failed or not.

@var boolean $fail The failing value.