How to use the pygeodesy.units.Lon function in PyGeodesy

x = self._x / r
        y = 2 * atan(exp(self._y / r)) - PI_2
        if datum is not None:
            _xinstanceof(Datum, datum=datum)
            E = datum.ellipsoid
            if not E.isEllipsoidal:
                raise _IsnotError(_ellipsoidal_, datum=datum)
            # 
            y = y / r
            if E.e:
                y -= E.e * atanh(E.e * tanh(y))  # == E.es_atanh(tanh(y))
            y *= E.a
            x *= E.a / r

        r = LatLon2Tuple(Lat(degrees90(y)), Lon(degrees180(x)))
        return self._xnamed(r)

def reset(self, lat0, lon0):
        '''Set or reset the center point of this azimuthal projection.

           @arg lat0: Center point latitude (C{degrees90}).
           @arg lon0: Center point longitude (C{degrees180}).

           @raise RangeError: Invalid B{C{lat0}} or B{C{lon0}}.

           @raise UnitError: Invalid B{C{lat0}} or B{C{lon0}}.
        '''
        self._latlon0 = LatLon2Tuple(Lat(         lat0,  name=_lat0_),
                                     Lon(_norm180(lon0), name=_lon0_))
        self._sc0     = tuple(sincos2d(self.lat0))
        self._radius  = None

def _2fllh(lat, lon, height=None):
    '''(INTERNAL) Convert lat, lon, height.
    '''
    # lat, lon = parseDMS2(lat, lon)
    return (Lat(lat, Error=WGRSError),
            Lon(lon, Error=WGRSError), height)

def _2fll(lat, lon, *unused):
    '''(INTERNAL) Convert lat, lon.
    '''
    # lat, lon = parseDMS2(lat, lon)
    return (Lat(lat, Error=GARSError),
            Lon(lon, Error=GARSError))

def _2fll(lat, lon, *unused):
    '''(INTERNAL) Convert lat, lon to 2-tuple of floats.
    '''
    # lat, lon = parseDMS2(lat, lon)
    return (Lat(lat, Error=GeohashError),
            Lon(lon, Error=GeohashError))

g, precision = _2garstr2(garef)

    lon = _ll(_Digits,  g,       0, _LonLen, 1, 720) + _LonOrig_M1_1
    lat = _ll(_Letters, g, _LonLen, _MinLen, 0, 359) + _LatOrig_M1
    if precision > 0:
        lon, lat = _ll2(lon, lat, g, _MinLen, _M2)
        if precision > 1:
            lon, lat = _ll2(lon, lat, g, _MinLen + 1, _M3)

    if center:  # ll = (ll * 2 + 1) / 2
        lon += 0.5
        lat += 0.5

    r = _Resolutions[precision]  # == 1.0 / unit
    r = LatLonPrec3Tuple(Lat(lat * r, Error=GARSError),
                         Lon(lon * r, Error=GARSError), precision)
    return _xnamed(r, nameof(garef))