// pest. Elegant, efficient grammars
// Copyright (C) 2016 DragoČ™ Tiselice
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
/// A `trait` that defines an input for a `Parser`.