This function is nearly identical to an iter() operating on u() function. Each member of <list> is passed to the result of fetching <attr> as %0, and the results are used to form a new list. Arguments %1, %2, ... are taken from <arg1>, <arg2>, ... respectively, if present.
In addition to any single character, <output delim> can also be the null- delimiter, @@, or a newline, %r. By default, input and output delimiters are both space.
> &ADD_ONE object=add(%0,1)
> say map(object/add_one,1 2 3 4 5)
You say, "2 3 4 5 6"