Include KnownValue into IsExpr
Clarification and motivation
This issue is linked to #225 (closed) and should be based on it.
There seems to be no case of IsExpr ex a
where KnownValue a
constitutes a problem, however we are required add the latter every time we use the former (where a
is generic).
We should include as such KnownValue
in IsExpr
Acceptance criteria
IsExpr ex a
includes KnownValue a
and every unnecessary use of KnownValue
is removed.