polybius.fyi/reveal.js/node_modules/underscore.string/ltrim.js

var makeString = require('./helper/makeString');
var defaultToWhiteSpace = require('./helper/defaultToWhiteSpace');
var nativeTrimLeft = String.prototype.trimLeft;

module.exports = function ltrim(str, characters) {
  str = makeString(str);
  if (!characters && nativeTrimLeft) return nativeTrimLeft.call(str);
  characters = defaultToWhiteSpace(characters);
  return str.replace(new RegExp('^' + characters + '+'), '');
};