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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 flag_calls(func):
 """Wrap a function to detect and flag when it gets called. This is a decorator which takes a function and wraps it in a function with a 'called' attribute. wrapper.called is initialized to False. The wrapper.called attribute is set to False right before each call to the wrapped function, so if the call fails it remains False. After the call completes, wrapper.called is set to True and the output is returned. Testing for truth in wrapper.called allows you to determine if a call to func() was attempted and succeeded."""


    # don't wrap twice
    if hasattr(func, 'called'):
        return func

    def wrapper(*args, **kw):
        wrapper.called = False
        out = func(*args, **kw)
        wrapper.called = True
        return out

    wrapper.called = False
    wrapper.__doc__ = func.__doc__
    return wrapper