module I18n::Backend::Flatten

def flatten_translations(locale, data, escape, subtree)

is true and Symbols are automatically stored as links.
Nested hashes are included in the flattened hash just if subtree

translations flattened.
the value is another hash) and return a hash with all
Receives a hash of translations (where the key is a locale and 
def flatten_translations(locale, data, escape, subtree)
  hash = {}
  flatten_keys(data, escape) do |key, value|
    if value.is_a?(Hash)
      hash[key] = value if subtree
    else
      store_link(locale, key, value) if value.is_a?(Symbol)
      hash[key] = value
    end
  end
  hash
end