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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_handler(self, grant_type):
 """ Return a function or method that is capable handling the ``grant_type`` requested by the client or return ``None`` to indicate that this type of grant type is not supported, resulting in an error response. """

        if grant_type == 'authorization_code':
            return self.authorization_code
        elif grant_type == 'refresh_token':
            return self.refresh_token
        elif grant_type == 'password':
            return self.password
        return None