Convert last "prog" exercises as functions exercises (intermediate commit)

subjects/doppelgangerprog.en.md

@@ -17,18 +17,22 @@ func DoppelGanger(s, substr string) int {
 ```go
 package main
 
-import "fmt"
+import (
+	piscine ".."
+
+	"fmt"
+)
 
 func main() {
 	var result int
 
-	result = DoppelGanger("aaaaaaa", "a")
+	result = piscine.DoppelGanger("aaaaaaa", "a")
 	fmt.Println(result) // 6
 
-	result = DoppelGanger("qwerty", "t")
+	result = piscine.DoppelGanger("qwerty", "t")
 	fmt.Println(result) // 4
 
-	result = DoppelGanger("a", "b")
+	result = piscine.DoppelGanger("a", "b")
 	fmt.Println(result) // -1
 }
 ```

subjects/findprevprimeprog.en.md

@@ -21,11 +21,15 @@ Here is a possible [program](TODO-LINK) to test your function :
 ```go
 package main
 
-import "fmt"
+import (
+	piscine ".."
+
+	"fmt"
+)
 
 func main() {
-	fmt.Println(FindPrevPrime(5))
-	fmt.Println(FindPrevPrime(4))
+	fmt.Println(piscine.FindPrevPrime(5))
+	fmt.Println(piscine.FindPrevPrime(4))
 }
 ```
 

subjects/sliceprog.en.md

@@ -2,7 +2,7 @@
 
 ### Instructions
 
-Write a **function** that replicates the javascript function `slice`.
+Write a **function** that replicates the JavaScript function `slice`.
 
 The function receives a slice of strings and one or more integers, and returns a slice of strings. The returned slice is part of the received one but cut from the position indicated in the first int, until the position indicated by the second int.
 
@@ -25,24 +25,28 @@ Here is a possible program to test your function :
 ```go
 package main
 
-import "fmt"
+import (
+	"fmt"
+
+	piscine ".."
+)
 
 func main(){
     a := []string{"coding", "algorithm", "ascii", "package", "golang"}
-    fmt.Println(Slice(a, 1))
-    fmt.Println(Slice(a, 2, 4))
-    fmt.Println(Slice(a, -3))
-    fmt.Println(Slice(a, -2, -1))
-    fmt.Println(Slice(a, 2, 0))
+    fmt.Printf("%#v\n", piscine.Slice(a, 1))
+    fmt.Printf("%#v\n", piscine.Slice(a, 2, 4))
+    fmt.Printf("%#v\n", piscine.Slice(a, -3))
+    fmt.Printf("%#v\n", piscine.Slice(a, -2, -1))
+    fmt.Printf("%#v\n", piscine.Slice(a, 2, 0))
 }
 ```
 
 ```console
 student@ubuntu:~/student/test$ go build
 student@ubuntu:~/student/test$ ./test
-[algorithm ascii package golang]
-[ascii package]
-[ascii package golang]
-[package]
-[]
+[]string{"algorithm", "ascii", "package", "golang"}
+[]string{"ascii", "package"}
+[]string{"ascii", "package", "golang"}
+[]string{"package"}
+[]string(nil)
 ```

tests/go/solutions/sliceprog/test_sliceprog.go

@@ -41,6 +41,6 @@ func main() {
 	}
 
 	for _, a := range arr {
-		z01.Challenge("SliceProg", student.Slice, correct.Slice, a...)
+		z01.Challenge("Slice", student.Slice, correct.Slice, a...)
 	}
 }