assert(_:_:file:line:)

An assertion that is active in DEBUG builds, just like Swift.assert and additionally if assertions are explicitly requested by setting the SWIFTSYNTAX_ENABLE_ASSERTIONS conditional compilation flag. Use this instead of precondition in places where the assertion has a non-trivial cost but provides little value in release builds.

Assert.swift:32
func assert(_ condition: @autoclosure () -> Bool, _ message: @autoclosure () -> String = String(), file: StaticString = #file, line: UInt = #line)