S9 LIB  (mode list)  ==>  list

        (load-from-library "mode.scm")

Return the mode(s) of a list of values. The mode of a set of samples
is the value that occurs most frequently. A set may be multi-modal,
i.e. have multiples modes.

(mode '(1 2 3 3 4 5 5 6))  ==>  (3 5)
