Remove-duplicates-equal requires that its argument
is a true list. Note that unlike remove-duplicates, it does not
allow string arguments.
Major Section: PROGRAMMING
Remove-duplicates-equal is the same as remove-duplicates,
except that its argument must be a true list (not a string), and
equal is used to check membership rather than eql.
See remove-duplicates.
The guard for Remove-duplicates-equal requires that its argument
is a true list. Note that unlike remove-duplicates, it does not
allow string arguments.