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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 method_call(receiver, message, args, pseudo_type=None):
    '''A shortcut for a method call, expands a str receiver to a identifier'''

    if not isinstance(receiver, Node):
        receiver = local(receiver)
    return Node('method_call', receiver=receiver, message=message, args=args, pseudo_type=pseudo_type)