src/Ko/SharedMemory.php
public function offsetExists($offset)
    {
        $task = function() use ($offset) {
            return shm_has_var($this->id, $this->getKey($offset));
        };

        return $this->mutex->lockExecute($task);
    }
public function offsetExists($offset)
    {
        $task = function() use ($offset) {
            return shm_has_var($this->id, $this->getKey($offset));
        };

        return $this->mutex->lockExecute($task);
    }
(PHP 5 &gt;= 5.0.0)<br/>
Whether a offset exists
@link http://php.net/manual/en/arrayaccess.offsetexists.php

@param mixed $offset <p>
An offset to check for.
</p>

@return boolean true on success or false on failure.
</p>
<p>
The return value will be casted to boolean if non-boolean was returned.