    def _RRDB(self, input_layer, t):
        """Residual in Residual Dense Block.

        t is integer, for naming of RRDB.
        beta is scalar.
        """
        
        # SUGGESTION: MAKE BETA LEARNABLE
        x = input_layer
        for d in range(1, self.D + 1):
            LFF = self._dense_block(x, d, t)
            LFF_beta = MultiplyBeta(self.beta)(LFF)
            x = Add(name='LRL_%d_%d' % (t, d))([x, LFF_beta])
        x = MultiplyBeta(self.beta)(x)
        x = Add(name='RRDB_%d_out' % (t))([input_layer, x])
        return x
Residual in Residual Dense Block.

t is integer, for naming of RRDB.
beta is scalar.
ISR/models/rrdn.py