class Temple::Filters::MultiFlattener

def compile(exp)
  return exp unless exp.first == :multi
  # If the multi contains a single element, just return the element
  return compile(exp[1]) if exp.length == 2
  result = [:multi]
  
  exp[1..-1].each do |e|
    e = compile(e)
    if e.first == :multi
      result.concat(e[1..-1])
    else
      result << e
    end
  end
  
  result
end