def get_num_fsaverage_verts_per_hemi(fsversion=6):
    """
    Return the number of vertices per fsaverage hemisphere.

    Returns
    -------
    vertcount: int
         The number of vertices per fsaverage hemisphere.
    """
    if fsversion == 6:
        return 163842
    else:
        raise ValueError("Currently the only supported FreeSurfer version is 6.")