Sequentially applies all tactics given by mapping a function over the
assumptions of a goal.
DESCRIBE
When applied to a theorem-tactic f and a goal ({A1,...,An} ?- C), the
EVERY_ASSUM tactical maps f over a list of ASSUMEd assumptions then
applies the resulting tactics, in sequence, to the goal:
EVERY_ASSUM f ({A1,...,An} ?- C)
= (f(A1 |- A1) THEN ... THEN f(An |- An)) ({A1,...,An} ?- C)
If the goal has no assumptions, then EVERY_ASSUM has no effect.
FAILURE
The application of EVERY_ASSUM to a theorem-tactic and a goal fails
if the theorem-tactic fails when applied to any of the ASSUMEd assumptions
of the goal, or if any of the resulting tactics fail when applied
sequentially.