# File lib/facebooker/rails/helpers.rb, line 831
  def assert_valid_keys(*valid_keys)
    unknown_keys = keys - [valid_keys + FB_ALWAYS_VALID_OPTION_KEYS].flatten
    raise(ArgumentError, "Unknown key(s): #{unknown_keys.join(", ")}") unless unknown_keys.empty?
  end

# File lib/facebooker/rails/helpers.rb, line 824
  def swapkey!( newkey, oldkey )
    self[newkey] = self.delete(oldkey) if self.has_key?(oldkey)
    self
  end

# File lib/facebooker/rails/helpers.rb, line 819
  def transform_key!(old_key, new_key)
    swapkey!(new_key, old_key)
  end

# File lib/facebooker/rails/helpers.rb, line 814
  def transform_keys!(transformation_hash)
    transformation_hash.each_pair{|key, value| transform_key!(key, value)}
  end