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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 add(self, kind, key, *values):
 """Add processor functions. Any previous list of processors for `kind` and `key` will be overwritten. Parameters kind : {"pre", "post"} key : str A registered key. Add the functions (in order) to this key's list of processors. *values : callables Processors to add. """

        if kind == "pre":
            procs = self.pre
        elif kind == "post":
            procs = self.post
        else:
            raise ValueError("kind is not 'pre' or 'post'")
        self._check_if_registered(key)
        procs[key] = values