code: function chkkey(key) {
          if (dst[key]) {
              var msg = Date.now() + " : merge clobbered " + key + ' with ' + src.slice(2) + '.' + key
              console.error(msg)
              dst['clobbered'].push(msg)
          }
          dst[key] = rsrc[key]
      }
docs: If something gets clobbered we log it and also append a timestamped message to dst['clobbered']