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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 build_rotation(vec3):
 """ Build a rotation matrix. vec3 is a Vector3 defining the axis about which to rotate the object. """

        if not isinstance(vec3, Vector3):
            raise ValueError("rotAmt must be a Vector3")
        return Matrix4.x_rotate(vec3.x) * Matrix4.y_rotate(vec3.y) * Matrix4.z_rotate(vec3.z)