Introspection of system version

[Frank]

Hello,

In the system definition we can specify a version; for example:

(asdf:defsystem :foo
  :description "foo utility"
  :license     "LGPL"

  :version (:read-file-form "VERSION")

  :serial t
  :components ((:file "foo")))

For example I can query the system license like this:
  (asdf:system-licence (asdf:find-system "foo"))

How can I query the version of system foo at run time?

Thanks,
Frank