EWW func add url under point as bookmark

[Alex]

When Im reading mails, or when Im in IRC or browsing pages with EWW,
sometimes I get an interesting url, then I want save it as eww bookmark
to read it in other moment.

I was searching a function that add a bookmark from the url under cursor
(point), but there aren't some like it.

I want write a func for it, so I was searching a func that add a
bookmark from a string.

Ex:
(defun eww-add-bookmark (&optional str)
      "Bookmark the current page or string"
         ...)

But `eww-add-bookmark' dont support arguments

Any help?