I have no idea what this is for but it was here

Signed-off-by: AKP <tom@tdpain.net>

helpers/cartesianProduct.go

@@ -0,0 +1,34 @@
+package helpers
+
+// The following two functions were taken and/or modified from https://stackoverflow.com/a/29023392
+
+func CartesianProduct(a []int, k int) <-chan []int {
+	c := make(chan []int)	
+	lens := len(a)
+	r := make([]int, k)
+	
+	go func(c chan []int) {
+		defer close(c)
+		for ix := make([]int, k); ix[0] < lens; nextIndex(ix, lens) {
+			for i, j := range ix {
+				r[i] = a[j]
+			}
+			c <- r
+		}
+	}(c)
+
+	return c
+}
+
+// nextIndex sets ix to the lexicographically next value,
+// such that for each i>0, 0 <= ix[i] < lens.
+func nextIndex(ix []int, lens int) {
+	// https://stackoverflow.com/a/29023392
+	for j := len(ix) - 1; j >= 0; j-- {
+		ix[j]++
+		if j == 0 || ix[j] < lens {
+			return
+		}
+		ix[j] = 0
+	}
+}

helpers/combinations.go

@@ -0,0 +1,26 @@
+package helpers
+
+
+// The following two functions were taken from https://stackoverflow.com/a/19249957
+
+func GenerateCombinations(alphabet string, length int) <-chan string {
+	c := make(chan string)
+	go func(c chan string) {
+		defer close(c)
+		addLetter(c, "", alphabet, length)
+	}(c)
+	return c
+}
+
+func addLetter(c chan string, combo string, alphabet string, length int) {
+	if length <= 0 {
+		return
+	}
+
+	var newCombo string
+	for _, ch := range alphabet {
+		newCombo = combo + string(ch)
+		c <- newCombo
+		addLetter(c, newCombo, alphabet, length-1)
+	}
+}