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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 estimate(path):
    '''
    Estimate the space that an XFS filesystem will take.
    For each directory estimate the space that directory would take
    if it were copied to an XFS filesystem.
    Estimation does not cross mount points.

    CLI Example:

    .. code-block:: bash

        salt '*' xfs.estimate /path/to/file
        salt '*' xfs.estimate /path/to/dir/*
    '''
    if not os.path.exists(path):
        raise CommandExecutionError("Path \"{0}\" was not found.".format(path))

    out = __salt__['cmd.run_all']("xfs_estimate -v {0}".format(path))
    _verify_run(out)

    return _xfs_estimate_output(out["stdout"])