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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 set_monitor_callback(cbfun):
 """ Sets the monitor configuration callback. Wrapper for: GLFWmonitorfun glfwSetMonitorCallback(GLFWmonitorfun cbfun); """

    global _monitor_callback
    previous_callback = _monitor_callback
    if cbfun is None:
        cbfun = 0
    c_cbfun = _GLFWmonitorfun(cbfun)
    _monitor_callback = (cbfun, c_cbfun)
    cbfun = c_cbfun
    _glfw.glfwSetMonitorCallback(cbfun)
    if previous_callback is not None and previous_callback[0] != 0:
        return previous_callback[0]