t('one.two.three.four')

path.split(".").inject(hash) { |hash, key| hash[key] }

def convert_hash(hash, path = "")
  hash.each_with_object({}) do |(k, v), ret|
    key = path + k

    if v.is_a? Hash
      ret.merge! convert_hash(v, key + ".")
    else
      ret[key] = v
    end
  end
end

class Hash
  def dig(dotted_path)
    parts = dotted_path.split '.', 2
    match = self[parts[0]]
    if !parts[1] or match.nil?
      return match
    else
      return match.dig(parts[1])
    end
  end
end

my_hash = {'a' => {'b' => 'a-b', 'c' => 'a-c', 'd' => {'e' => 'a-d-e'}}, 'f' => 'f'}
my_hash.dig('a.d.e') # outputs 'a-d-e' (by calling my_hash['a']['d']['e'])