code: def metres2latlon(mx, my, origin_shift= 2 * pi * 6378137 / 2.0):
      
      lon = (mx / origin_shift) * 180.0
      lat = (my / origin_shift) * 180.0
  
      lat = 180 / pi * (2 * atan( exp( lat * pi / 180.0)) - pi / 2.0)
      return lat, lon
docs: Converts XY point from Spherical Mercator EPSG:900913 to lat/lon in
      WGS84 Datum