async def health_check(self) -> Iterator[HealthCheckFail]:
ds_class = getattr(settings, '<STR_LIT>', '<STR_LIT>')<EOL>forbidden_defaults = [None, '<STR_LIT>', '<STR_LIT>']<EOL>if ds_class in forbidden_defaults:<EOL><INDENT>yield HealthCheckFail(<EOL>'<STR_LIT>',<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>)<EOL><DEDENT>try:<EOL><INDENT>import_class(ds_class)<EOL><DEDENT>except (ImportError, KeyError, AttributeError, TypeError):<EOL><INDENT>yield HealthCheckFail(<EOL>'<STR_LIT>',<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>f'<STR_LIT>'<EOL>)<EOL><DEDENT>states = set(t.dest for t in self.transitions)<EOL>for state in states:<EOL><INDENT>async for check in state.health_check():<EOL><INDENT>yield check<EOL><DEDENT><DEDENT>
Perform the checks. So far:

- Make a list of the unique destination states from the transitions
  list, then check the health of each of them.