class ActiveSupport::HashWithIndifferentAccess

def transform_keys!(hash = NOT_GIVEN, &block)
  return to_enum(:transform_keys!) if NOT_GIVEN.equal?(hash) && !block_given?
  if hash.nil?
    super
  elsif NOT_GIVEN.equal?(hash)
    keys.each { |key| self[yield(key)] = delete(key) }
  elsif block_given?
    keys.each { |key| self[hash[key] || yield(key)] = delete(key) }
  else
    keys.each { |key| self[hash[key] || key] = delete(key) }
  end
  self
end