# File lib/erubis/engine/escheme.rb, line 28
    def add_preamble(src)
      return unless @func == '_add'
      src << "(let ((_buf '())) " + \
               "(define (_add x) (set! _buf (cons x _buf))) "
      #src << "(let* ((_buf '())" +        #             " (_add (lambda (x) (set! _buf (cons x _buf))))) "
    end