in format.go [140:151]
func (un *formatter) WriteNewLine() (int, error) {
if un.err != nil {
return 0, un.err
}
if !un.options.pretty {
return 0, nil
}
un.lastWrappedIndex = un.dst.Len()
var n int
n, un.err = un.dst.WriteNewLine(un.indent)
return n, un.err
}