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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 _dict_key_priority(s):
 """Return priority for a given key object."""

        if isinstance(s, Hook):
            return _priority(s._schema) - 0.5
        if isinstance(s, Optional):
            return _priority(s._schema) + 0.5
        return _priority(s)