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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_enable_branch(desired_branch):
 """Enable desired branch name."""

    preserved_branch = _git_get_current_branch()
    try:
        if preserved_branch != desired_branch:
            _tool_run('git checkout ' + desired_branch)
        yield
    finally:
        if preserved_branch and preserved_branch != desired_branch:
            _tool_run('git checkout ' + preserved_branch)