code: function(str, to) {
      if (isUndefined(to)) to = str.length;
      return str.slice(0, numberOrIndex(str, to));
    }
docs: *
  @method to([index] = end)
  @returns String
  @short Returns a section of the string ending at [index].
  
  @example
  
  'lucky charms'.to()   -> 'lucky charms'
  'lucky charms'.to(7)  -> 'lucky ch'
  
  @param {number} [index]
  
  *