Most functions for format builders set `self.result` after writing strings. This ensures that any further writing fails immediately rather than trying to write again. A few `.finish()` methods did have this same behavior, so make it consistent here.
Most functions for format builders set `self.result` after writing strings. This ensures that any further writing fails immediately rather than trying to write again. A few `.finish()` methods did have this same behavior, so make it consistent here.