function report( last, current, loc ) {
		context.report({
			'node': null,
			'message': '"'+current+'" should come before "'+last+'"',
			'loc': loc
		});
	}
Reports the error message.

@private
@param {string} last - name of first package
@param {string} current - name of second package
@param {Object} loc - lines of code (object with `start` and `end` properties)