package main

import (
    "fmt"
    "math"
)

func sqrt(x float64) string {
    // just like any other programming language's
    // if statement
    if x < 0 {
        return sqrt(-x) + "i"
    }

    // quick way to convert the value to a string
    return fmt.Sprint(math.Sqrt(x))
}

func main() {
    fmt.Println(sqrt(2), sqrt(-4))
}