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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 get_wrapper_by_cls(env, cls):
 """Returns the gym env wrapper of the given class, or None."""

    currentenv = env
    while True:
        if isinstance(currentenv, cls):
            return currentenv
        elif isinstance(currentenv, gym.Wrapper):
            currentenv = currentenv.env
        else:
            return None