code: function copy(color, out) {
      if (out !== undefined) {
          out[0] = color[0];
          out[1] = color[1];
          out[2] = color[2];
          out[3] = color[3];
          return out;
      }
      return color.slice(0);
  }
docs: ### copy() Copies rgba values from another color into this instance `c` - another color to copy values from *{ Color }* 
  Copies color
  @param  {Array} color - color to copy
  @param  {Array} [out] - color to copy values into
  @return {Array} - new RGBA color array [r,g,b,a] (0..1) or updated out color