code: def dot (self, other):
      
      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)
docs: dot (self, other) -> number
  
      Returns the dot product of this Point with another.