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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 git_hash():
 """returns the current git hash or unknown if not in git repo"""

    if git_repo() is None:
        return "unknown"
    git_hash = subprocess.check_output(
        ["git", "rev-parse", "HEAD"])
    # git_hash is a byte string; we want a string.
    git_hash = git_hash.decode("utf-8")
    # git_hash also comes with an extra \n at the end, which we remove.
    git_hash = git_hash.strip()
    return git_hash