`Easy`	`Codewriting` 	`300`

Given an array of integers, replace all the occurrences of `elemToReplace` with `substitutionElem`.

## Example

- For `inputArray = [1, 2, 1]`, `elemToReplace = 1`, and `substitutionElem = 3`, the output should be
`arrayReplace(inputArray, elemToReplace, substitutionElem) = [3, 2, 3]`.

## Input/Output

- [execution time limit] 4 seconds (go)

- [input] array.integer inputArray

    Guaranteed constraints: \
    `0 ≤ inputArray.length ≤ 104`, \
    `0 ≤ inputArray[i] ≤ 109`.

- [input] integer elemToReplace

    Guaranteed constraints: \
    `0 ≤ elemToReplace ≤ 109`.

- [input] integer substitutionElem

    Guaranteed constraints: \
    `0 ≤ substitutionElem ≤ 109`.

- [output] array.integer

## [Go] Syntax Tips

``` go
// Prints help message to the console
// Returns a string
func helloWorld(name string) string {
    fmt.Printf("This prints to the console when you Run Tests");
    return "Hello, " + name;
}
```
