anchor.diff:      DeltaLat = MaxLat - MinLat,
       DeltaLon = MaxLon - MinLon,
       Bits = geohash_bits(DeltaLat, DeltaLon, 63),
  -    Bits/5.
  +    trunc(Bits/5).
   
   %% @doc Determine the bounding box of coordinates for a point and radius
   %% distance on the earth.
  
positive.code: %% @doc Calculate 8 neighboring geohashes
  -spec neighbors(binary()) -> [binary()].
  neighbors(C) ->
      N = neighbor(C, u),
      W = neighbor(C, l),
      S = neighbor(C, d),
      E = neighbor(C, r),
      NW = neighbor(N, l),
      NE = neighbor(N, r),
      SW = neighbor(S, l),
      SE = neighbor(S, r),
      [N, W, S, E, NW, NE, SW, SE].
  
  %% @doc Expand a geohash to give a list of itself and 8 neighboring geohashes
  
negative.code: -spec nearby(float(), float(), float()) -> [binary()].
  nearby(Lat, Lon, Rad) ->
      Precision = nearby_precision(Lat, Lon, Rad),
      {ok, GeoHash} = encode(Lat, Lon, Precision),
      expand(GeoHash).
  
  %% @private
  