src/transformers/models/ibert/quant_modules.py/IntGELU/forward
class IntGELU:    def forward(self, x, scaling_factor=None):
        if not self.quant_mode:
            return self.activation_fn(x), None

        x_int = x / scaling_factor
        sigmoid_int, sigmoid_scaling_factor = self.int_erf(x_int, scaling_factor / self.k)

        shift_int = 1.0 // sigmoid_scaling_factor

        x_int = x_int * (sigmoid_int + shift_int)
        scaling_factor = scaling_factor * sigmoid_scaling_factor / 2

        return x_int * scaling_factor, scaling_factor