diff --git a/.github/workflows/unit-test.yml b/.github/workflows/unit-test.yml
index ea15f39..42cd86d 100644
--- a/.github/workflows/unit-test.yml
+++ b/.github/workflows/unit-test.yml
@@ -10,7 +10,7 @@ jobs:
           fetch-depth: 2
       - uses: actions/setup-go@v2
         with:
-          go-version: '1.18'
+          go-version: '1.20'
       - name: Run tests with coverage
         run: go test -coverprofile=coverage.out -covermode=count ./...
       - uses: codecov/codecov-action@v2
@@ -20,4 +20,4 @@ jobs:
           flags: unittests
           name: codecov-umbrella
           fail_ci_if_error: true
-          verbose: true
\ No newline at end of file
+          verbose: true
diff --git a/Makefile b/Makefile
index 074cbde..5baa33d 100644
--- a/Makefile
+++ b/Makefile
@@ -14,6 +14,7 @@ scan:
 scan-config:
 	trivy config .
 
+.PHONY: docs
 docs:
 	cd docs && hugo server -D
 
diff --git a/docs/content/_index.md b/docs/content/_index.md
index f717fe2..cbaaacb 100644
--- a/docs/content/_index.md
+++ b/docs/content/_index.md
@@ -9,10 +9,9 @@ title: _Underscore
 
 ![underscore](https://socialify.git.ci/rjNemo/underscore/image?description=1&font=KoHo&language=1&logo=https%3A%2F%2Fraw.githubusercontent.com%2FrjNemo%2Funderscore%2Fmain%2Fdocs%2Fstatic%2Flogo.png&owner=1&pattern=Floating%20Cogs&stargazers=1&theme=Dark)
 
-
 `underscore` is a `Go` library providing useful functional programming helpers without extending any built-in objects.
 
-It is mostly a port from the `underscore.js` library based on generics brought by `go1.18`.
+It is mostly a port from the `underscore.js` library based on generics available from `go1.18`.
 
 ## Quick Start
 
diff --git a/docs/content/collections/groupby.md b/docs/content/collections/groupby.md
new file mode 100644
index 0000000..04cb548
--- /dev/null
+++ b/docs/content/collections/groupby.md
@@ -0,0 +1,21 @@
+---
+title: "Group by"
+date: 2023-06-07T00:49:56+02:00
+---
+
+GroupBy splits a slice into a map[K][]V grouped by the result of the iterator function.
+
+```go
+package main
+
+import (
+	"fmt"
+	u "github.com/rjNemo/underscore"
+)
+
+func main() {
+  	nums := []float64{1.3, 2.1, 2.4}
+	groupingFunc := func(n float64) int { return int(math.Floor(n)) }
+  	res := u.GroupBy(nums, groupingFunc) // { 1: {1.3}, 2: {2.1, 2.4}}
+}
+```
diff --git a/go.mod b/go.mod
index 371f6eb..a75f661 100644
--- a/go.mod
+++ b/go.mod
@@ -1,14 +1,14 @@
 module github.com/rjNemo/underscore
 
-go 1.18
+go 1.20
 
 require (
-	github.com/stretchr/testify v1.7.0
-	golang.org/x/exp v0.0.0-20220314205449-43aec2f8a4e7
+	github.com/stretchr/testify v1.8.4
+	golang.org/x/exp v0.0.0-20230522175609-2e198f4a06a1
 )
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/go.sum b/go.sum
index 99f8a6a..925e02e 100644
--- a/go.sum
+++ b/go.sum
@@ -1,15 +1,12 @@
-github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
-github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
-github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-golang.org/x/exp v0.0.0-20220314205449-43aec2f8a4e7 h1:jynE66seADJbyWMUdeOyVTvPtBZt7L6LJHupGwxPZRM=
-golang.org/x/exp v0.0.0-20220314205449-43aec2f8a4e7/go.mod h1:lgLbSvA5ygNOMpwM/9anMpWVlVJ7Z+cHWq/eFuinpGE=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+golang.org/x/exp v0.0.0-20230522175609-2e198f4a06a1 h1:k/i9J1pBpvlfR+9QsetwPyERsqu1GIbi967PQMq3Ivc=
+golang.org/x/exp v0.0.0-20230522175609-2e198f4a06a1/go.mod h1:V1LtkGg67GoY2N1AnLN78QLrzxkLyJw7RJb1gzOOz9w=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
-gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=