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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 pop_parameter(key):
    '''Remove and get parameter by key.

    Args:
        key(str): Key of parameter.

    Returns: ~nnabla.Variable
        Parameter if key found, otherwise None.

    '''
    names = key.split('/')
    if len(names) > 1:
        with parameter_scope(names[0]):
            return pop_parameter('/'.join(names[1:]))
    global current_scope
    param = current_scope.get(key, None)
    if param is not None:
        del current_scope[key]
    return param