Values will be indices 0, 1, 2...
Groups dimensions together for splitting or merging.
(h d) → h×d as one dimensionbatch (h w c) -> batch h w cAdds a singleton dimension of size 1.
h w -> 1 h wb h w -> b h w 1Matches any number of dimensions.
... d -> ... 1 dWorks with unknown batch dims
Use descriptive names for clarity.
Common: batch, seq, heightMust match on both sides!