coordsToPoint method
Implementation
@override
Vector3 coordsToPoint(Vector3 coords) {
  var origin = xAxis.n2p(0);
  var result = origin.copy();
  for (var d in IterableZip([coords.toList(), getAxes().submobjects])) {
    var axis = d[1] as NumberLine;
    var coord = d[0] as double;
    result += (axis.n2p(coord) - origin);
  }
  return result;
}