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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_keys(self, key=None):
 """ Returns a list of valid sub-keys. """

        if key:
            value = _lxc.Container.get_keys(self, key)
        else:
            value = _lxc.Container.get_keys(self)

        if value is False:
            return False
        elif value.endswith("\n"):
            return value.rstrip("\n").split("\n")
        else:
            return value