func SplitQuotedFields(s string) ([]string, error) {
	var f []string
	for len(s) > 0 {
		for len(s) > 0 && isSpaceByte(s[0]) {
			s = s[1:]
		}
		if len(s) == 0 {
			break
		}
		if s[0] == '"' || s[0] == '\'' {
			quote := s[0]
			s = s[1:]
			i := 0
			for i < len(s) && s[i] != quote {
				i++
			}
			if i >= len(s) {
				return nil, fmt.Errorf("unterminated %c string", quote)
			}
			f = append(f, s[:i])
			s = s[i+1:]
			continue
		}
		i := 0
		for i < len(s) && !isSpaceByte(s[i]) {
			i++
		}
		f = append(f, s[:i])
		s = s[i:]
	}
	return f, nil
}
SplitQuotedFields splits s into a list of fields,
allowing single or double quotes around elements.
There is no unescaping or other processing within
quoted fields.
package str
import (
	"bytes"
	"fmt"
	"unicode"
	"unicode/utf8"
)
func StringList(args ...interface{}) []string {
	var x []string
	for _, arg := range args {
		switch arg := arg.(type) {
		case []string:
			x = append(x, arg...)
		case string:
			x = append(x, arg)
		default:
			panic("stringList: invalid argument of type " + fmt.Sprintf("%T", arg))
		}
	}
	return x
}
func ToFold(s string) string {
	for i := 0; i < len(s); i++ {
		c := s[i]
		if c >= utf8.RuneSelf || 'A' <= c && c <= 'Z' {
			goto Slow
		}
	}
	return s
Slow:
	var buf bytes.Buffer
	for _, r := range s {
		for {
			r0 := r
			r = unicode.SimpleFold(r0)
			if r <= r0 {
				break
			}
		}
		if 'A' <= r && r <= 'Z' {
			r += 'a' - 'A'
		}
		buf.WriteRune(r)
	}
	return buf.String()
}
func FoldDup(list []string) (string, string) {
	clash := map[string]string{}
	for _, s := range list {
		fold := ToFold(s)
		if t := clash[fold]; t != "" {
			if s > t {
				s, t = t, s
			}
			return s, t
		}
		clash[fold] = s
	}
	return "", ""
}
func Contains(x []string, s string) bool {
	for _, t := range x {
		if t == s {
			return true
		}
	}
	return false
}
func isSpaceByte(c byte) bool {
	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
}