text: #include "ast.hpp"
  #include <iostream>
  int main(int argc, char **argv)
  {
      if (argc != 2) {
          std::cout << "usage: " << argv[0] << " <cminus_file>" << std::endl;
      } else  {
          auto s = parse(argv[1]);
          auto a = AST(s);
          auto printer = ASTPrinter();
          a.run_visitor(printer);
      }
      return 0;
  }
  