function onFinish( error, time ) {
		if ( error ) {
			return done( error );
		}
		results[ idx ] = time;
		idx += 1;
		if ( idx < opts.repeats ) {
			return next( onFinish );
		}
		done( null, results );
	}
Callback invoked upon executing code.

@private
@param {(Error|null)} error - error object
@param {NonNegativeIntegerArray} time - results
@returns {void}