center'``, ``'lower center'``, ``'center left'``,
    ``'center right'`` place the legend at the center of the corresponding edge
    of the {parent}.

    The string ``'center'`` places the legend at the center of the {parent}.
{best}
    The location can also be a 2-tuple giving the coordinates of the lower-left
    corner of the legend in {parent} coordinates (in which case *bbox_to_anchor*
    will be ignored).

    For back-compatibility, ``'center right'`` (but no other location) can also
    be spelled ``'right'``, and each "string" location can also be given as a
    numeric value:

        ==================   =============
        Location String      Location Code
        ==================   =============
        'best' (Axes only)   0
        'upper right'        1
        'upper left'         2
        'lower left'         3
        'lower right'        4
        'right'              5
        'center left'        6
        'center right'       7
        'lower center'       8
        'upper center'       9
        'center'             10
        ==================   =============
    {outside}a/