diff --git a/vlib/arrays/arrays.v b/vlib/arrays/arrays.v
index 76228c17d1..b45c815e43 100644
--- a/vlib/arrays/arrays.v
+++ b/vlib/arrays/arrays.v
@@ -154,7 +154,7 @@ pub fn group[T](arrs ...[]T) [][]T {
 }
 
 // chunk array into a single array of arrays where each element is the next `size` elements of the original.
-// Example: arrays.chunk([1, 2, 3, 4, 5, 6, 7, 8, 9], 2)) // => [[1, 2], [3, 4], [5, 6], [7, 8], [9]]
+// Example: arrays.chunk([1, 2, 3, 4, 5, 6, 7, 8, 9], 2) // => [[1, 2], [3, 4], [5, 6], [7, 8], [9]]
 pub fn chunk[T](array []T, size int) [][]T {
 	// allocate chunk array
 	mut chunks := [][]T{cap: array.len / size + if array.len % size == 0 { 0 } else { 1 }}
@@ -425,11 +425,10 @@ pub fn group_by[K, V](array []V, grouping_op fn (val V) K) map[K][]V {
 }
 
 // concatenate an array with an arbitrary number of additional values.
-//
-// NOTE: if you have two arrays, you should simply use the `<<` operator directly
-// Example: arrays.concat([1, 2, 3], 4, 5, 6) == [1, 2, 3, 4, 5, 6] // => true
-// Example: arrays.concat([1, 2, 3], ...[4, 5, 6]) == [1, 2, 3, 4, 5, 6] // => true
-// Example: arr << [4, 5, 6] // does what you need if arr is mutable
+// NOTE: if you have two arrays, you should simply use the `<<` operator directly.
+// Example: assert arrays.concat([1, 2, 3], 4, 5, 6) == [1, 2, 3, 4, 5, 6]
+// Example: assert arrays.concat([1, 2, 3], ...[4, 5, 6]) == [1, 2, 3, 4, 5, 6]
+// Example: mut arr := arrays.concat([1, 2, 3], 4); arr << [10,20]; assert arr == [1,2,3,4,10,20] // note: arr is mutable
 pub fn concat[T](a []T, b ...T) []T {
 	mut m := []T{cap: a.len + b.len}
 
diff --git a/vlib/arrays/index_of.v b/vlib/arrays/index_of.v
index f00bda7292..96ff1a6ba3 100644
--- a/vlib/arrays/index_of.v
+++ b/vlib/arrays/index_of.v
@@ -2,7 +2,7 @@ module arrays
 
 // index_of_first returns the index of the first element of `array`, for which the predicate fn returns true.
 // If predicate does not return true for any of the elements, then index_of_first will return -1.
-// Example: arrays.index_of_first([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 2
+// Example: assert arrays.index_of_first([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 2
 pub fn index_of_first[T](array []T, predicate fn (idx int, elem T) bool) int {
 	for i, e in array {
 		if predicate(i, e) {
@@ -14,7 +14,7 @@ pub fn index_of_first[T](array []T, predicate fn (idx int, elem T) bool) int {
 
 // index_of_last returns the index of the last element of `array`, for which the predicate fn returns true.
 // If predicate does not return true for any of the elements, then index_of_last will return -1.
-// Example: arrays.index_of_last([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 4
+// Example: assert arrays.index_of_last([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 4
 pub fn index_of_last[T](array []T, predicate fn (idx int, elem T) bool) int {
 	for i := array.len - 1; i >= 0; i-- {
 		e := array[i]
diff --git a/vlib/arrays/map_of.v b/vlib/arrays/map_of.v
index 31448c1c11..784a2aab42 100644
--- a/vlib/arrays/map_of.v
+++ b/vlib/arrays/map_of.v
@@ -2,7 +2,7 @@ module arrays
 
 // map_of_indexes returns a map, where each key is an unique value in `array`.
 // Each value in that map for that key, is an array, containing the indexes in `array`, where that value has been found.
-// Example: arrays.map_of_indexes([1,2,3,4,4,2,1,4,4,999]) == {1: [0, 6], 2: [1, 5], 3: [2], 4: [3, 4, 7, 8], 999: [9]}
+// Example: assert arrays.map_of_indexes([1,2,3,4,4,2,1,4,4,999]) == {1: [0, 6], 2: [1, 5], 3: [2], 4: [3, 4, 7, 8], 999: [9]}
 pub fn map_of_indexes[T](array []T) map[T][]int {
 	mut result := map[T][]int{}
 	for i, e in array {
@@ -18,7 +18,7 @@ pub fn map_of_indexes[T](array []T) map[T][]int {
 // map_of_counts returns a map, where each key is an unique value in `array`.
 // Each value in that map for that key, is how many times that value occurs in `array`.
 // It can be useful for building histograms of discrete measurements.
-// Example: arrays.map_of_counts([1,2,3,4,4,2,1,4,4]) == {1: 2, 2: 2, 3: 1, 4: 4}
+// Example: assert arrays.map_of_counts([1,2,3,4,4,2,1,4,4]) == {1: 2, 2: 2, 3: 1, 4: 4}
 pub fn map_of_counts[T](array []T) map[T]int {
 	mut result := map[T]int{}
 	for e in array {