API design help: Wrapping ITensorMPS structs and extending it to my package

Hi Julia community! I am currently developing a package, ProcessTensors.jl, that uses an MPS/MPO architecture to construct process tensors and simulate non-Markovian quantum dynamics. I built this package on top of the features offered in ITensors.jl and ITensorMPS.jl. Since I am a big fan of these two packages and find their user interface appealing (thank you, @mtfishman!), I wanted to have the same API experience in my package as well. However, I also need to add some more abstraction on top...