unbound local variable is_global

[joshdempster]

Trying to call est_spectra with a gene_set_dict of the form {"global": dict of gene sets} and use_cell_types=False leads to an unbound local variable error for is_global after training. Looking through the code, this happens because in this case, check_gene_set_dictionary expects a single-layered dict for gene_set_dict. This behavior isn't in the doc string. A couple suggestions:

• Either change this so the expected format of gene_set_dict is consistent (my personal preference), or else have check_gene_set_dictionary check if global_key is in the top layer of gene_set_dict before wrapping it in another layer.
• Expand the doc string for est_spectra to be more explicit about the format and put an example of the format in the README
• No matter what, check that gene_set_dict is not empty after all changes are made to it and before training

[Tobiaspk]

Hi, thanks for raising this issue and your suggestions. PR #35 contains a new check that gene_set_dict is not empty. Agreed, ideally the format of gene_set_dict is consistent. This should also be updated in the next release.