docs: function load(source) {
    var redis
      , method
      , script
      , name
      , digest;
  
    digest = sha1hex(source);
    if(this._cache[digest]) {
      return {script: this._cache[digest], sha: digest};
    }
  
    name = 'f_' + digest;
  
    method = util.format(
      'var method = function %s(KEYS, ARGS, cb) {%s}', name, source);
  
    // declare the method
    try {
      script = vm.createScript(method, name);
    }catch(e) {
      return process.send(
        {
          err: true,
          data: 'error compiling script (new function): user_script: '
            + e.message});
    }
  
    // cache the method by digest
    this._cache[digest] = script;
    log.debug('script load: %s', digest);
    return {sha: digest, script: script};
  }