func braceIndices(s string) ([]int, error) {
	var level, idx int
	idxs := make([]int, 0)
	for i := 0; i < len(s); i++ {
		switch s[i] {
		case '{':
			if level++; level == 1 {
				idx = i
			}
		case '}':
			if level--; level == 0 {
				idxs = append(idxs, idx, i+1)
			} else if level < 0 {
				return nil, fmt.Errorf("mux: unbalanced braces in %q", s)
			}
		}
	}
	if level != 0 {
		return nil, fmt.Errorf("mux: unbalanced braces in %q", s)
	}
	return idxs, nil
}
func braceIndices(s string) ([]int, error) {
	var level, idx int
	idxs := make([]int, 0)
	for i := 0; i < len(s); i++ {
		switch s[i] {
		case '{':
			if level++; level == 1 {
				idx = i
			}
		case '}':
			if level--; level == 0 {
				idxs = append(idxs, idx, i+1)
			} else if level < 0 {
				return nil, fmt.Errorf("mux: unbalanced braces in %q", s)
			}
		}
	}
	if level != 0 {
		return nil, fmt.Errorf("mux: unbalanced braces in %q", s)
	}
	return idxs, nil
}
func braceIndices ( s string ) ( [ ] int , error ) { var level , idx int idxs := make ( [ ] int , 0 ) for i := 0 ; i < len ( s ) ; i ++ { switch s [ i ] { case '{' : if level ++ ; level == 1 { idx = i } case '}' : if level -- ; level == 0 { idxs = append ( idxs , idx , i + 1 ) } else if level < 0 { return nil , fmt . Errorf ( " " , s ) } } } if level != 0 { return nil , fmt . Errorf ( " " , s ) } return idxs , nil }
// braceIndices returns the first level curly brace indices from a string.
// It returns an error in case of unbalanced braces.
braceIndices returns the first level curly brace indices from a string . It returns an error in case of unbalanced braces .