NMFList-class: Class for Storing Heterogeneous NMF fits
Description
This class wraps a list of NMF fit objects, which may
come from different runs of the function
nmf, using different parameters, methods,
etc.. These can be either from a single run (NMFfit) or
multiple runs (NMFfitX).
Note that its definition/interface is very likely to
change in the future.