code: function (cols) {
              cols = argsToArray(arguments);
              var currentSelect = this.__opts.select;
              return this.select.apply(this, (currentSelect || []).concat(cols));
          }
docs: Returns a copy of the dataset with the given columns added
  to the existing selected columns. If no columns are currently selected
  it will just select the columns given.
  
  @example
  DB.from("items").select("a").select("b").sql;
  //=> SELECT b FROM items
  
  DB.from("items").select("a").selectMore("b", "c", "d").sql
  //=> SELECT a, b, c, d FROM items
  
  DB.from("items").selectMore("b").sql
  //=> SELECT b FROM items
  
  @param [...] cols variable number of columns to add to the select statement
  
  @return {patio.Dataset} returns a cloned dataset with the new select columns appended.