my own perl imenu. Default imenu provides too many information for me

cperl-imenu.el

(defun my/cperl-imenu-create-index ()
  (let (index)
    ;; collect subroutine
    (goto-char (point-min))
    (while (re-search-forward "^\\s-*sub\\s-+\\([^ ]+\\)" nil t)
      (push (cons (format "Function: %s" (match-string 1))
                  (match-beginning 1)) index))

    ;; collect subtest
    (goto-char (point-min))
    (let ((desc-re "^\\s-*subtest\\s-+\\(['\"]\\)\\([^\1\r\n]+\\)\\1"))
      (while (re-search-forward desc-re nil t)
        (push (cons (format "Subtest: %s" (match-string 2))
                    (match-beginning 2)) index)))
    (nreverse index)))