Function max_pool2d 

pub fn max_pool2d(
    input: &Tensor,
    kernel_size: (usize, usize),
    stride: Option<(usize, usize)>,
    padding: (usize, usize),
    dilation: (usize, usize),
    ceil_mode: bool,
    return_indices: bool,
) -> Result<(Tensor, Option<Tensor>)>

2D max pooling