Returns the first element of a non-empty iterable.Given a non-empty Iterable xs with a linearization of [x1, ..., xN], front(xs) is equal to x1. If xs is empty, it is an error to use this function. Equivalently, front(xs) must be equivalent to at_c<0>(xs), and that regardless of the value category of xs (front must respect the reference semantics of at). More...
Louis Dionne 2013-2016 Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
