v1.7.1

New Features

• Add UNSET singleton
• nullable dataclass overhaul (#607)
  • Update nullable_dc to use UNSET instead of None
  • Rename mk_dataclass to flexiclass
  • flexiclass uses UNSET instead of None
• Add asdict, like the dataclasses version but works on more types
• Add is_typeddict and is_namedtuple
• Flatten nested tuples in ft