class Sass::CSS

def flatten_rule(rule)
  while rule.children.size == 1 && rule.children.first.is_a?(Tree::RuleNode)
    child = rule.children.first
    if first_simple_sel(child).is_a?(Sass::Selector::Parent)
      rule.parsed_rules = child.parsed_rules.resolve_parent_refs(rule.parsed_rules)
    else
      rule.parsed_rules = make_seq(*(first_seq(rule).members + first_seq(child).members))
    end
    rule.children = child.children
  end
  flatten_rules(rule)
end