def list_project_files(self, folder):
        pfiles = []
        library = os.path.join(folder, "library.json")
        if os.path.exists(library):
            j = JsonFile(library)
            for f in j.load([]):
                if os.path.exists(f) and f not in pfiles:
                    pfiles.append(os.path.normpath(f))
            pfiles.sort()
            j.save(pfiles)
        for path, dirs, files in os.walk(folder, followlinks=True):
            for f in files:
                f = os.path.join(path, f)
                if f.endswith(".sublime-project") and pfiles not in f:
                    pfiles.append(os.path.normpath(f))
            # remove empty directories
            for d in dirs:
                d = os.path.join(path, d)
                if len(os.listdir(d)) == 0:
                    os.rmdir(d)
        return pfiles
dataset/ETHPy150Open randy3k/Project-Manager/pm.py/Manager.list_project_files/swapped operands of `not in`