# code_block0.py

from numpy import cos, sin


class Point(object):
    """3D Points objects"""

    x = 0.0
    y = 0.0
    z = 0.0

    def rotate_z(self, theta):
        """rotate the point around the Z axis"""
        xtemp = cos(theta) * self.x + sin(theta) * self.y
        ytemp = -sin(theta) * self.x + cos(theta) * self.y
        self.x = xtemp
        self.y = ytemp
