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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 read_remote_origin(repo_dir):
 """Read the remote origin URL from the given git repo, or None if unset."""

    conf = ConfigParser()
    conf.read(os.path.join(repo_dir, '.git/config'))
    return conf.get('remote "origin"', 'url')