color(from, to, factor) {
    const c0 = helpersColor(from || transparent);
    const c1 = c0.valid && helpersColor(to || transparent);
    return c1 && c1.valid
      ? c1.mix(c0, factor).hexString()
      : to;
  }
@param {string} from
@param {string} to
@param {number} factor