#assert preprocessing extensions of
System V release 4 are permitted. These enable definition and testing
of predicate names.
Such names are in a namespace distinct from all other names, including macro names.
A predicate name defined using
be tested in a
#if expression, for example:
This has the value 1 if a
#assert of the
and 0 otherwise. A given predicate can be given more than one value
at a given time.