meaning of shape parameter in to_tt_matrix?

[Ujjawal-K-Panchal]

I have been trying to use the tensor decomposition on a personal project from your to_tt_matrix and to_tt_tensor. However, I donot understand what the additional shape parameter in t3nsor.decompositions.to_tt_matrix() stand for.

Your comments in the code suggest it can also contain None values, which to me is quite puzzling. Would appreciate your answer on this.