tool/documentation.js
function mkdirp(dirpath, callback) {
  fs.exists(dirpath, function(exists) {
    if (exists) return callback(dirpath);
    mkdirp(path.dirname(dirpath), () => fs.mkdir(dirpath, callback));
  });
}
function mkdirp(dirpath, callback) {
  fs.exists(dirpath, function(exists) {
    if (exists) return callback(dirpath);
    mkdirp(path.dirname(dirpath), () => fs.mkdir(dirpath, callback));
  });
}
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