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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 read_validate_params(self, request):
 """ Checks if all incoming parameters meet the expected values. """

        self.client = self.client_authenticator.by_identifier_secret(request)

        self.password = request.post_param("password")
        self.username = request.post_param("username")

        self.scope_handler.parse(request=request, source="body")

        return True