class Hash
  
  def deep_merge(other_hash)
    self.merge(other_hash) do |key, oldval, newval|
      oldval = oldval.to_hash if oldval.respond_to?(:to_hash)
      newval = newval.to_hash if newval.respond_to?(:to_hash)
      oldval.class.to_s == 'Hash' && newval.class.to_s == 'Hash' ? oldval.deep_merge(newval) : newval
    end
  end unless method_defined?(:deep_merge)

end