diff --git a/scribblings/networks.scrbl b/scribblings/networks.scrbl
index 110fc0a..51d2bab 100644
--- a/scribblings/networks.scrbl
+++ b/scribblings/networks.scrbl
@@ -62,6 +62,24 @@ their domains.
 
 }
 
+@section{Common examples}
+
+The examples in this document often use the same definitions, which are
+therefore grouped here to avoid duplicating them.
+
+These are two functions calculating an @italic{AND} and an @italic{OR} between
+the variables @racket[a] and @racket[b]:
+
+@ex[
+(: or-func (UpdateFunction Boolean))
+(define (or-func s)
+  (or (hash-ref s 'a) (hash-ref s 'b)))
+
+(: and-func (UpdateFunction Boolean))
+(define (and-func s)
+  (and (hash-ref s 'a) (hash-ref s 'b)))
+]
+
 @section{Networks}
 
 @defstruct*[network ([functions (VariableMapping (UpdateFunction a))]
@@ -79,14 +97,6 @@ Instances of @racket[network] have the type @racket[Network].
 The type of the instances of @racket[Network].
 
 @ex[
-(: or-func (UpdateFunction Boolean))
-(define (or-func s)
-  (or (hash-ref s 'a) (hash-ref s 'b)))
-
-(: and-func (UpdateFunction Boolean))
-(define (and-func s)
-  (and (hash-ref s 'a) (hash-ref s 'b)))
-
 (network (hash 'a or-func
                'b and-func)
          (hash 'a '(#f #t)
@@ -119,14 +129,6 @@ Builds a Boolean network from a given hash table assigning functions to
 variables by attributing Boolean domains to every variable.
 
 @ex[
-(: or-func (UpdateFunction Boolean))
-(define (or-func s)
-  (or (hash-ref s 'a) (hash-ref s 'b)))
-
-(: and-func (UpdateFunction Boolean))
-(define (and-func s)
-  (and (hash-ref s 'a) (hash-ref s 'b)))
-
 (make-boolean-network (hash 'a or-func 'b and-func))
 ]}