is_uexists : term -> bool

SYNOPSIS: Tests if a term is of the form `there exists a unique ...'
DESCRIPTION: If t has the form ?!x. p[x] (there exists a unique x such that p[x] then is_uexists t returns true, otherwise false.
FAILURE CONDITIONS: Never fails.
SEE ALSO: dest_uexists, is_exists, is_forall.