dest_res_exists : term -> (term # term # term)
STRUCTURE
res_quanLib
SYNOPSIS
Breaks apart a restricted existentially quantified term into the quantified variable, predicate and body.
DESCRIPTION
dest_res_exists is a term destructor for restricted existential quantification: 
   dest_res_exists "?var::P. t"
returns ("var","P","t").
FAILURE
Fails with dest_res_exists if the term is not a restricted existential quantification.
SEEALSO
mk_res_exists, is_res_exists, strip_res_exists
HOL  Kananaskis-14