anchor.diff:  (defun download-arguments (url target-dir)
     "Return a list of arguments for the download command.
   
  -Appends `*download-args' and -o /target/directory/%(title)s.%(ext)s (for youtube-dl)."
  +Uses `*download-args*' and sets the output file path."
     (declare (ignorable url))
     (append *download-args* (list "-o" (format nil "~a/%(title)s.%(ext)s" target-dir))))
   
  
positive.code: (in-package :next)
  
  (define-command download-video ()
    "Download the video of the current URL with an external program."
    (let* ((url (url (current-buffer))))
      (cond
        ((null next/video::*preferred-download-directories*)
  
negative.code: 
  (declaim (type (or null string) *download-program*))
  (defparameter *download-program* "youtube-dl"
    "The external program to download videos with.")
  
  (declaim (type (or null list-of-strings) *download-args*))
  (defparameter *download-args* nil
    "Default arguments for the download command as a list of strings. See also the `download-arguments' function which extends the arguments.")
  
  ;; TODO: Make browser's download-path a list.
  (declaim (type (or null list) *preferred-download-directories*))
  