What's the meaning of self.if_bidirectional

[Lxg-233]

what‘s the self.if_bidirectional,I konw that we define bimaba_type=v1/v2 in mamba_simple.py to present we use bidirectional ssm. So what's the meaning of self.if_bidirectional in models_mamba.py，I don't know it,please help me.
thanks !

       if not self.if_bidirectional: 
       ..............
        else: 
            # get two layers in a single for-loop
            for i in range(len(self.layers) // 2): #
                if self.if_rope:
                    hidden_states = self.rope(hidden_states)
                    if residual is not None and self.if_rope_residual:
                        residual = self.rope(residual)

                hidden_states_f, residual_f = self.layers[i * 2](  
                    hidden_states, residual, inference_params=inference_params
                )
                hidden_states_b, residual_b = self.layers[i * 2 + 1](   
                    hidden_states.flip([1]), None if residual == None else residual.flip([1]), inference_params=inference_params
                )
                hidden_states = hidden_states_f + hidden_states_b.flip([1]) 
                residual = residual_f + residual_b.flip([1])

[Lxg-233]

I really hlep!!!