module Geocoder::Util

h1.merge!(h2) #=> {"a" => 100, "b" = >254, "c" => {"c1" => 16, "c3" => 94}}

Simply using Hash#merge! would return

recursive_hash_merge(h1, h2) #=> {"a" => 100, "b" => 254, "c" => {"c1" => 16, "c2" => 14, "c3" => 94}}
h2 = {"b" => 254, "c" => {"c1" => 16, "c3" => 94}}
h1 = {"a" => 100, "b" => 200, "c" => {"c1" => 12, "c2" => 14}}

it merges and returns the values from both hashes.
When both +h1+ and +h2+ contains an entry with the same key,
Compared with Hash#merge!, this method supports nested hashes.

merging entries in +h1+ with duplicate keys with those from +h2+.
Adds the contents of +h2+ to +h1+,

Recursive version of Hash#merge!

def self.recursive_hash_merge(h1, h2)
  h1.merge!(h2) do |_key, oldval, newval|
    oldval.class == h1.class ? self.recursive_hash_merge(oldval, newval) : newval
  end
end