The following changes have been made to the code with respect to <https://github.com/edlund/amalgamate/commit/c91f07eea1133aa184f652b8f1398eaf03586208>:

- Resolved inspection results from PyCharm:
    - replaced tabs with spaces
    - added encoding annotation
    - reindented file to remove trailing whitespaces
    - unused import `sys`
    - membership check
    - made function from `_is_within`
    - removed unused variable `actual_path`
