module HashRecursiveMerge

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

Simply using Hash#merge! would return

h1.rmerge!(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 arrays.
When both +hsh+ and +other_hash+ contains an entry with the same key,
Compared with Hash#merge!, this method supports nested hashes.

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

Recursive version of Hash#merge!

def rmerge!(other_hash)
  merge!(other_hash) do |key, oldval, newval|
    oldval.class == self.class ? oldval.rmerge!(newval) : newval
  end
end