make execute a regular function not a method

rover.fnl

@@ -46,14 +46,13 @@
 (fn execute [rover [cmd & cmds]]
   (let [r1 (command rover cmd)]
     (if (next cmds)
-        (r1:execute cmds)
+        (execute r1 cmds)
         r1)))
 
 (fn rover [x y direction]
   {: x
    : y
    : direction
-   : execute
    })
 
 (let [r (rover 7 15 :n)]
@@ -64,41 +63,41 @@
 
 (let [r (rover 0 0 :n)]
   (expect "The rover receives a character array of commands"
-          (r:execute [:f :f :f])
+          (execute r [:f :f :f])
           {}))
 
 (let [r (rover 0 0 :n)]
   (expect "Moves north when pointing north and asked to move forward"
-          (r:execute [:f]) {:x 0 :y 1 :direction :n}))
+          (execute r [:f]) {:x 0 :y 1 :direction :n}))
 
 (let [r (rover 3 2 :s)]
   (expect "Moves south when pointing south and asked to move forward"
-          (r:execute [:f]) {:x 3 :y 1 :direction :s}))
+          (execute r [:f]) {:x 3 :y 1 :direction :s}))
 
 (let [r (rover 0 0 :w)]
   (expect "Moves west when pointing west and asked to move forward"
-          (r:execute [:f]) {:x -1 :y 0 :direction :w}))
+          (execute r [:f]) {:x -1 :y 0 :direction :w}))
 
 (let [r (rover 0 0 :e)]
   (expect "Moves east when pointing east and asked to move forward"
-          (r:execute [:f]) {:x 1 :y 0 :direction :e}))
+          (execute r [:f]) {:x 1 :y 0 :direction :e}))
 
 (let [r (rover 1 1 :s)]
   (expect "The rover acts on multiple commands"
-          (r:execute [:f :f :f])
+          (execute r [:f :f :f])
           {:x 1 :y -2 :direction :s}))
 
 (let [r (rover 2 4 :e)]
   (expect "Rotates to south when pointing east and asked to turn right"
-          (r:execute [:r]) {:x 2 :y 4 :direction :s}))
+          (execute r [:r]) {:x 2 :y 4 :direction :s}))
 
 (let [r (rover 2 4 :s)]
   (expect "Rotates to east when pointing south and asked to turn left"
-          (r:execute [:l]) {:x 2 :y 4 :direction :e}))
+          (execute r [:l]) {:x 2 :y 4 :direction :e}))
 
 (let [r (rover 2 4 :w)]
   (expect "Rotates to north when pointing west and asked to turn right"
-          (r:execute [:r]) {:x 2 :y 4 :direction :n}))
+          (execute r [:r]) {:x 2 :y 4 :direction :n}))
 
 
 (print "OK")