In srfi-152.sld, the definitions of

    string->utf16be
    string-utf16le
    utf16be->string
    utf16le->string

aren't right.  The first two ignore their one argument, and none
of the four accept the optional arguments specified by SRFI 152.

(test "substring" "cde" (substring "abcde" 2))

(test "string-replicate" "cdefab"
       (string-replicate "abcdef" 2))
(test "string-replicate" "efabcd"
       (string-replicate "abcdef" -2))