code: function getTweenVal(pos, units, begin, end, k, i, v) {
      if (k == 'transform') {
        v = {}
        for (var t in begin[i][k]) {
          v[t] = (t in end[i][k]) ? Math.round(((end[i][k][t] - begin[i][k][t]) * pos + begin[i][k][t]) * thousand) / thousand : begin[i][k][t]
        }
        return v
      } else if (typeof begin[i][k] == 'string') {
        return nextColor(pos, begin[i][k], end[i][k])
      } else {
        // round so we don't get crazy long floats
        v = Math.round(((end[i][k] - begin[i][k]) * pos + begin[i][k]) * thousand) / thousand
        // some css properties don't require a unit (like zIndex, lineHeight, opacity)
        if (!(k in unitless)) v += units[i][k] || 'px'
        return v
      }
    }
docs: this retreives the frame value within a sequence