code: def point_to_index(self, point):
          
          indices = points_to_indices(points=[point],
                                      pitch=self.pitch,
                                      origin=self.origin)
          index = tuple(indices[0])
          return index
docs: Convert a point to an index in the matrix array.
  
          Parameters
          ----------
          point: (3,) float, point in space
  
          Returns
          ---------
          index: (3,) int tuple, index in self.matrix