strip_imp : term -> term list * term
STRUCTURE
boolSyntax
SYNOPSIS
Iteratively breaks apart implications.
DESCRIPTION
If M is of the form t1 ==> (... (tn ==> t) ...), then strip_imp M returns ([t1,...,tn],t). Note that 
   strip_imp(list_mk_imp([t1,...,tn],t))
will not return ([t1,...,tn],t) if t is an implication.
FAILURE
Never fails.
EXAMPLE
- strip_imp "(T ==> F) ==> (T ==> F)";;
> val it = (["T ==> F"; "T"], "F") : term list * term

- strip_imp (Term `t1 ==> t2 ==> t3 ==> ~t`);
> val it = ([`t1`, `t2`, `t3`, `t`], `F`) : term list * term

SEEALSO
list_mk_imp, dest_imp
HOL  Kananaskis-14