class SyntaxTree::MatchVisitor

def pairs(name, values)
  q.group do
    q.text(name)
    q.text(": [")
    q.indent do
      q.breakable("")
      q.seplist(values) do |(key, value)|
        q.group do
          q.text("[")
          q.indent do
            q.breakable("")
            visit(key)
            q.text(",")
            q.breakable
            visit(value || nil)
          end
          q.breakable("")
          q.text("]")
        end
      end
    end
    q.breakable("")
    q.text("]")
  end
end