function done( error, response ) {
		var info;
		if ( arguments.length === 1 ) {
			debug( 'No available rate limit information.' );
			return clbk( error );
		}
		debug( 'Request completed.' );

		// Get rate limit information:
		info = ratelimit( response.headers );
		debug( 'Rate limit: %d', info.limit );
		debug( 'Rate limit remaining: %d', info.remaining );
		debug( 'Rate limit reset: %s', (new Date( info.reset*1000 )).toISOString() );

		if ( error ) {
			return clbk( error, info );
		}
		clbk( null, info );
	}
Callback invoked after completing request.

@private
@param {(Error|null)} error - error object
@param {Object} response - HTTP response object
@returns {void}