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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def matrix(self, angle):
 """Return rotation matrix in homogeneous coordinates."""

        _rot_mat = {
            'x': self._x_rot,
            'y': self._y_rot,
            'z': self._z_rot
        }
        return _rot_mat[self.axis](angle)