Unzipstring function

subjects/unzipstring/README.md

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+## Unzipstring
+
+
+### Instructions
+
+Unzipstring is a simple function that takes a string in of form of a number and an alphabet like (2a) and returns the original string (aa).
+
+- the number before the alphabet should be between 0 to 9 
+- The one  alphabet after each number should be  between a to z or A to Z
+- it can be two numbers or two alphabets in a row
+- if the Input string doesn't respect the format return `Invalid Input`
+
+
+### Expected Function
+
+```go
+func Unzipstring(s string) string {
+    //code here
+}
+```
+
+### Usage
+
+Here is a possible program to test your function:
+
+```go
+
+package main
+
+import (
+    "fmt"
+    "piscine"
+)
+
+func main() {
+    fmt.Println(piscine.Unzipstring("6H8a"))
+    fmt.Println(piscine.Unzipstring("3p6i1W"))
+    fmt.Println(piscine.Unzipstring("2O5u2H0e"))
+    fmt.Println(piscine.Unzipstring("2f"))
+    fmt.Println(piscine.Unzipstring("2a 6p8f"))
+    fmt.Println(piscine.Unzipstring("2p4;7g"))
+    fmt.Println(piscine.Unzipstring("2t4dD"))
+    fmt.Println(piscine.Unzipstring("82t4D"))
+
+}
+```
+
+And its output :
+
+```console
+$ go run .
+HHHHHaaaaaaaa
+pppiiiiiiWWW
+OOuuuuuHH
+ff
+Invalid Input
+Invalid Input
+Invalid Input
+Invalid Input
+
+```