whole_func_string: function mkdirp(dirpath, callback) {
    fs.exists(dirpath, function(exists) {
      if (exists) return callback(dirpath);
      mkdirp(path.dirname(dirpath), () => fs.mkdir(dirpath, callback));
    });
  }
func_code_string: function mkdirp(dirpath, callback) {
    fs.exists(dirpath, function(exists) {
      if (exists) return callback(dirpath);
      mkdirp(path.dirname(dirpath), () => fs.mkdir(dirpath, callback));
    });
  }
func_documentation_string: 创建所有目录