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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 _check_action(action):
 """check for invalid actions"""

    if isinstance(action, types.StringTypes):
        action = action.lower()

    if action not in ['learn', 'forget', 'report', 'revoke']:
        raise SpamCError('The action option is invalid')
    return action