Function flatten

ServerEditorWeb/ace/worker-javascript.js:1664–1676

(input, shallow, output)

    return _.filter(array, _.identity);
  };
  var flatten = function(input, shallow, output) {
    if (shallow && _.every(input, _.isArray)) {
      return concat.apply(output, input);
    }
    each(input, function(value) {
      if (_.isArray(value) || _.isArguments(value)) {
        shallow ? push.apply(output, value) : flatten(value, shallow, output);
      } else {
        output.push(value);
      }
    });
    return output;
  };
  _.flatten = function(array, shallow) {
    return flatten(array, shallow, []);
  };