code: def from_geo(geo, level):
      
      pixel = TileSystem.geo_to_pixel(geo, level)
      tile = TileSystem.pixel_to_tile(pixel)
      key = TileSystem.tile_to_quadkey(tile, level)
      return QuadKey(key)
docs: Constucts a quadkey representation from geo and level
      geo => (lat, lon)
      If lat or lon are outside of bounds, they will be clipped
      If level is outside of bounds, an AssertionError is raised