package
static if(!(UDAs.length == 0))
static if(is(typeof(UDAs[0])))
static if(is(T == S!E, alias S, E))
static if(!(anySatisfy!(isSame!S, PullSource, PeekSource, PushSource, AllocSource)))
static if(!(anySatisfy!(isSame!S, PullSink, PeekSink, PushSink, AllocSink)))
= .