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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_strategy(name_or_cls):
 """Return the strategy identified by its name. If ``name_or_class`` is a class, it will be simply returned. """

    if isinstance(name_or_cls, six.string_types):
        if name_or_cls not in STRATS:
            raise MutationError("strat is not defined")
        return STRATS[name_or_cls]()

    return name_or_cls()