class Hash

def deep_merge(other_hash, &block)
  dup.deep_merge!(other_hash, &block)
end if !{}.respond_to?(:deep_merge)

def deep_merge!(other_hash, &block)
  other_hash.each_pair do |k,v|
    tv = self[k]
    if tv.is_a?(Hash) && v.is_a?(Hash)
      self[k] = tv.deep_merge(v, &block)
    else
      self[k] = block && tv ? block.call(k, tv, v) : v
    end
  end
  self
end if !{}.respond_to?(:deep_merge!)

def stringify_keys
  keys.each do |key|
    self[key.to_s] = delete(key)
  end
  self
end if !{}.respond_to?(:stringify_keys)

def symbolize_keys
  keys.each do |key|
    self[(key.to_sym rescue key) || key] = delete(key)
  end
  self
end if !{}.respond_to?(:symbolize_keys)