"it" is common in that sense, but muse additionally models "the" as a function that turns verbs into nouns - like we do. For example,

    (open-file "blah" 'for-writing)
    (write (the open-file) "hello world")
    (close it)

Or

    (length (list "milk" "pudding"))
    (print "number of items is " (the length))