HELP LOOKUP                              updated Mark Rubinstein  October 1985

This procedure takes one argument, and searches the database to see if it
matches anything there.  If so the first matching item is set to be the value
of the variable *IT and if the argument is a pattern containing variables,
they will get bound (see HELP * MATCH).  If no matching item is found in the
database, a mishap results.  It could be defined thus:

    define lookup(pattern);
        unless present(pattern) then
            mishap('lookup failure', [%pattern%])
        endunless
    enddefine;
