def METHOD_NAME(self, frames):
    """Convert a list of 2d frames into a padded 3d tensor
    Args:
        frames (list): list of 2d frames of size L[i]*f_dim. Where L[i] is
            length of i-th frame and f_dim is static dimension of features
    Returns:
        3d tensor of size len(frames)*len_max*f_dim where len_max is max of L[i]
    """
    len_max = max(frame.size(0) for frame in frames)
    f_dim = frames[0].size(1)
    res = frames[0].new(len(frames), len_max, f_dim).fill_(0.0)
    for i, v in enumerate(frames):
        res[i, : v.size(0)] = v
    return res