## trimatoi
### Instructions
- Write a function that transforms a number within a `string` , in an `int` .
- For this exercise the handling of the `-` sign **has** to be taken into account. If the sign is encountered before any number it should determine the sign of the returned `int` .
- This function will **only** return an `int` . In case of invalid input, the function should return `0` .
- **Note**: There will never be more than one sign by `string` in the tests.
### Expected function
```go
func TrimAtoi(s string) int {
}
```
### Usage
Here is a possible program to test your function :
```go
package main
import (
"fmt"
"piscine"
)
func main() {
fmt.Println(piscine.TrimAtoi("12345"))
fmt.Println(piscine.TrimAtoi("str123ing45"))
fmt.Println(piscine.TrimAtoi("012 345"))
fmt.Println(piscine.TrimAtoi("Hello World!"))
fmt.Println(piscine.TrimAtoi("sd+x1fa2W3s4"))
fmt.Println(piscine.TrimAtoi("sd-x1fa2W3s4"))
fmt.Println(piscine.TrimAtoi("sdx1-fa2W3s4"))
fmt.Println(piscine.TrimAtoi("sdx1+fa2W3s4"))
}
```
And its output :
```console
$ go run .
12345
12345
12345
0
1234
-1234
1234
1234
$
```
