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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 commit_hash(self):
 """Return the current commit hash if available. This is not a required task so best effort is fine. In other words this is not guaranteed to work 100% of the time. """

        commit_hash = None
        branch = None
        branch_file = '.git/HEAD'  # ref: refs/heads/develop

        # get current branch
        if os.path.isfile(branch_file):
            with open(branch_file, 'r') as f:
                try:
                    branch = f.read().strip().split('/')[2]
                except IndexError:
                    pass

            # get commit hash
            if branch:
                hash_file = '.git/refs/heads/{}'.format(branch)
                if os.path.isfile(hash_file):
                    with open(hash_file, 'r') as f:
                        commit_hash = f.read().strip()
        return commit_hash