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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 _validate_xoxp_token(self):
 """Ensures that an xoxp token is used when the specified method is called. Raises: BotUserAccessError: If the API method is called with a Bot User OAuth Access Token. """


        if self.token.startswith("xoxb"):
            method_name = inspect.stack()[1][3]
            msg = "The method '{}' cannot be called with a Bot Token.".format(
                method_name
            )
            raise err.BotUserAccessError(msg)