def h3_to_geo(h3_index)
      coords = GeoCoord.new
      Bindings::Private.h3_to_geo(h3_index, coords)
      [rads_to_degs(coords[:lat]), rads_to_degs(coords[:lon])]
    end
def h3_to_geo(h3_index)
      coords = GeoCoord.new
      Bindings::Private.h3_to_geo(h3_index, coords)
      [rads_to_degs(coords[:lat]), rads_to_degs(coords[:lon])]
    end
Derive coordinates for a given H3 index.

 The coordinates map to the centre of the hexagon at the given index.

 @param [Integer] h3_index A valid H3 index.

 @example Derive the central coordinates for the given H3 index.
   H3.h3_to_geo(617439284584775679)
   [52.245519061399506, -1.7363137757391423]

 @return [Array<Integer>] A coordinate pair.