Select from two lists at the same position. True if XList is
unifiable with YList apart a single element at the same position
that is unified with X in XList and with Y in YList. A typical use
for this predicate is to replace an element, as shown in the
example below. All possible substitutions are performed on
?- select(b, [a,b,c,b], 2, X).
X = [a, 2, c, b] ;
X = [a, b, c, 2] ;