class FilterTable::Trace

def self.to_ruby(trace)
  chain = trace.instance_variable_get(:@chain)
  return '' if chain.empty?
  ' ' + chain.map do |el|
    m = el[0][0]
    args = el[0].drop(1)
    nxt = to_ruby(el[1])
    next m.to_s + nxt if args.empty?
    next m.to_s + ' ' + args[0].inspect + nxt if args.length == 1
    m.to_s + '(' + args.map(&:inspect).join(', ') + ')' + nxt
  end.join(' ')
end

def initialize
  @chain = []
end

def method_missing(*args)
  res = Trace.new
  @chain.push([args, res])
  res
end