They provide BSD-3-licensed Python files but the interesting bit happens in the shared object library, which is only provided in binary form (but is also BSD-3-licensed it seems, so you can distribute it freely).
Since it is under the BSD 3 licence, users would also be permitted to decompile and modify the shared object under the licence terms.
Since it is under the BSD 3 licence, users would also be permitted to decompile and modify the shared object under the licence terms.