lexpro_nullsafety 1.0.1

lexpro for sound null safety refactoring version.

lexpro nullsafety version

Will merge into lexpro 3, support sound nullsafety.

If the sdk version in your project is higher than 2.12 please change lexpro to lexpro_nullsafety in pubspec.yaml,

To see more usage please visit lexpro 2