Does not work on Python3.7

[sobolevn]

Source code I am trying to fix: https://gist.githubusercontent.com/sobolevn/f22c44f303746a82b49e2499036ec4ce/raw/530070984f867b79ccd441c03b63e361d628202a/views.py

Output:

» python -m star_destroyer ex.py

=== IMPORT MAPPINGS ===

=== ORIGINS USED ===
Traceback (most recent call last):
  File "/Users/sobolev/.pyenv/versions/3.7.7/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/Users/sobolev/.pyenv/versions/3.7.7/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/Users/sobolev/Documents/github/returns/.venv/lib/python3.7/site-packages/star_destroyer.py", line 376, in <module>
    edit(modules, import_map, usage_map, actually_write=False)
  File "/Users/sobolev/Documents/github/returns/.venv/lib/python3.7/site-packages/star_destroyer.py", line 335, in edit
    star_destroyer = StarDestroyer(import_map, usage_map)
  File "/Users/sobolev/Documents/github/returns/.venv/lib/python3.7/site-packages/star_destroyer.py", line 257, in __init__
    for modpath in usage_map.get_modpaths()))
TypeError: descriptor 'union' of 'set' object need