function cmp(a, b, op) {
						switch (op) {
							case 'eq':
							case '==':
								return a === b;
							case 'lt':
							case '<':
								return a < b;
							case 'lte':
							case '<=':
								return a <= b;
							case 'gt':
							case '>':
								return a > b;
							case 'gte':
							case '>=':
								return a >= b;
						}
					}
Helper module to work with ranges