def deep_merge!(other_hash)
      merge!(other_hash) do |_key, oldval, newval|
        oldval.class == self.class ? oldval.deep_merge!(newval) : newval
      end
    end
def deep_merge!(other_hash)
      merge!(other_hash) do |_key, oldval, newval|
        oldval.class == self.class ? oldval.deep_merge!(newval) : newval
      end
    end
Recursive version of Hash#merge!

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

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

    h1 = {"a" => 100, "b" => 200, "c" => {"c1" => 12, "c2" => 14}}
    h2 = {"b" => 254, "c" => 300, "c" => {"c1" => 16, "c3" => 94}}
    h1.rmerge!(h2)   #=> {"a" => 100, "b" => 254,
                          "c" => {"c1" => 16, "c2" => 14, "c3" => 94}}

 Simply using Hash#merge! would return

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