docs: def merge_dict(lhs, rhs):
      """ Merge content of a dict in another
  
      :param: dict: lhs
        dict where is merged the second one
      :param: dict: rhs
        dict whose content is merged
      """
      assert isinstance(lhs, dict)
      assert isinstance(rhs, dict)
      for k, v in rhs.iteritems():
          if k not in lhs:
              lhs[k] = v
          else:
              lhs[k] = merge_dict(lhs[k], v)
      return lhs