Golang将列表对象转换为字符串

I have two structs:

type A struct {
    BankCode           string `json:"bankCode"`
    BankName           string `json:"bankName"`
}

And:

type B struct {
    A 
    extra           string `json:" extra"`
}

listsA []AlistsB []BbankCodeslistAlistBbankcodesbankcodes[]string

It will be so easy as using two function.

func getBankCodes(data []A) []string {
    res := make([]string, len(data))
    for i := 0; i < len(data); i++ {
        res[i] = data[i].BankCode
    }
    return res
}

func getBankCodes(data []B) []string {
    res := make([]string, len(data))
    for i := 0; i < len(data); i++ {
        res[i] = data[i].BankCode
    }
    return res
}

How to use one common function ?