internal/logfmt/logfmt.go
func WriteKeyValue(buf Writer, key, value interface{}) {
	writeKey(buf, key)
	buf.WriteRune('=')
	WriteValue(buf, value)
}
func WriteKeyValue(buf Writer, key, value interface{}) {
	writeKey(buf, key)
	buf.WriteRune('=')
	WriteValue(buf, value)
}
// WriteKeyValue writes a key/value pair to the writer.