convert fallback location estimators to be iterators

my/location/fallback/all.py

@@ -1,17 +1,24 @@
 # TODO: add config here which passes kwargs to estimate_from (under_accuracy)
 # overwritable by passing the kwarg name here to the top-level estimate_location
 
-from typing import Union
-from datetime import datetime
+from typing import Iterator
 
-from my.location.fallback.common import estimate_from, FallbackLocation
+from my.core.source import import_source
+from my.location.fallback.common import estimate_from, FallbackLocation, DateExact
 
-def estimate_location(dt: Union[datetime, float, int]) -> FallbackLocation:
+# note: the import_source returns an iterator
+@import_source(module_name="my.location.fallback.via_home")
+def _home_estimate(dt: DateExact) -> Iterator[FallbackLocation]:
     from my.location.fallback.via_home import estimate_location as via_home
 
+    yield from via_home(dt)
+
+
+
+def estimate_location(dt: DateExact) -> FallbackLocation:
     loc = estimate_from(
          dt,
-         estimators=(via_home,)
+         estimators=(_home_estimate,)
     )
     if loc is None:
         raise ValueError("Could not estimate location")