closes PR 10927

collects/2htdp/image.rkt

@@ -115,9 +115,9 @@ and they all have good sample contracts. (It is amazing what we can do with kids
          
          make-color
          make-pen
-         
-         save-image
-         )
+         pen?
+         step-count?
+         save-image)
 
 (provide bitmap)
 

collects/teachpack/2htdp/scribblings/image.scrbl

@@ -968,6 +968,10 @@ The baseline of an image is the place where the bottoms any letters line up, not
   greater than or equal to @scheme[3].
 }
 
+@defproc[(step-count? [x any/c]) boolean?]{
+  Determines if @racket[x] is an integer greater than or equal to @racket[1].                                           
+}
+
 @defstruct[pen ([color image-color?]
                 [width (and/c real? (<=/c 0 255))]
                 [style pen-style?]