code: function(loc, left, right) {
  			var a, b;
  			if (loc instanceof Range) {
  				a = loc.start;
  				b = loc.end;
  			} else {
  				a = b = loc;
  			}
  			
  			return cmp(this.start, a, left || '<=') && cmp(this.end, b, right || '>');
  		}
docs: Low-level comparision method
  @param {Number} loc
  @param {String} left Left comparison operator
  @param {String} right Right comaprison operator