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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def repo_id(self, repo: str) -> str: """ Returns an unique identifier from a repo URL for the folder the repo is gonna be pulled in. """

        if repo.startswith("http"):
            repo_id = re.sub(r"https?://(.www)?", "", repo)
            repo_id = re.sub(r"\.git/?$", "", repo_id)
        else:
            repo_id = repo.replace("file://", "")
            repo_id = re.sub(r"\.git/?$", "", repo_id)
            if repo_id.startswith("~"):
                repo_id = str(Path(repo_id).resolve())

        # replaces everything that isn't alphanumeric, a dot or an underscore
        # to make sure it's a valid folder name and to keep it readable
        # multiple consecutive invalid characters replaced with a single underscore
        repo_id = re.sub(r"[^a-zA-Z0-9._]+", "_", repo_id)

        # and add a hash of the original to make it absolutely unique
        return repo_id + hashlib.sha256(repo.encode("utf-8")).hexdigest()