code: function pushArr(path, obj, val) {
    path = path.split('/')
    path.forEach(function(subPath) {
      if (Array.isArray(obj[subPath])) return obj[subPath].push(val)
      obj = obj[subPath]
    })
  }
docs: Push a value to an array nested in an object. @param {String} path @param {Object} opts @param {Object} obj @param {Any} value