docs: function scale(x, offset) {
        var mappedIndex = dateIndexMap[+x];
        offset = offset || 0;
  
        // Make sure the value has been mapped, if not, determine if it's just before, round in, or just after domain
        if(mappedIndex === undefined) {
          if(domain[0] > x) mappedIndex = -1; // Less than min, round just out of domain
          else mappedIndex = d3_bisect(domain, x); // else let bisect determine where in or just after than domain it is
        }
  
        return index(mappedIndex + offset);
      }