The docs 1 give the arguments as:
        tensor – an n-dimensional torch.Tensor

        a – the negative slope of the rectifier used after this layer (only used with 'leaky_relu')

        mode – either 'fan_in' (default) or 'fan_out'. Choosing 'fan_in' preserves the magnitude of the variance of the weights in the forward pass. Choosing 'fan_out' preserves the magnitudes in the backwards pass.

        nonlinearity – the non-linear function (nn.functional name), recommended to use only with 'relu' or 'leaky_relu' (default).