code: function() {
      var table = {}
      // Invert 'alphabet'
      for (var i = 0; i < alphabet.length; i++) {
          table[alphabet[i]] = i
      }
      // Splice in 'alias'
      for (var key in alias) {
          if (!alias.hasOwnProperty(key)) continue
          table[key] = table['' + alias[key]]
      }
      lookup = function() { return table }
      return table
  }
docs: Build a lookup table and memoize it
  
  Return an object that maps a character to its
  byte value.