Golang方法：方法就是一个包含了接受者的函数

package main

import (
    "fmt"
    "math"
)

func main() {
    getSquareRoot := func(x float64) float64 {  //等价于func getSquareRoot1(x float64) float64{}
        return math.Sqrt(x)
    }

    fmt.Println(getSquareRoot(9))
    fmt.Println(getSquareRoot1(16))
}

func getSquareRoot1(x float64) float64 {
    return math.Sqrt(x)
}