docs: def dot (self, other):
      """dot (self, other) -> number
  
      Returns the dot product of this Point with another.
      """
      if self.z:
        return (self.x * other.x) + (self.y * other.y) + (self.z * other.z)
      else:
        return (self.x * other.x) + (self.y * other.y)