/**
* Sets the start time.
*
* @param double $startTime Unix timestamp in microseconds for setting the Profiler start time.
* @param int $startMem Memory amount in bytes for setting the Profiler start memory.
*
* @return $this For chaining
*
* @since 3.0.0
*/
public function setStart($startTime = 0.0, $startMem = 0)
{
$this->start = (double) $startTime;
$this->previousMem = (int) $startMem / 1048576;
return $this;
}