fix: use overloads to properly type itertracks

Add overloads for itertracks so that its return type is properly reflected when
passed literal True or False (or nothing). Previously, when type checking

for segment, track_name, label in annotation.itertracks(yield_label=True): ...

the type checker would complain that the iterator could contain 2-tuples. A
similar issue existed when passing False.

pyannote/core/annotation.py

@@ -121,11 +121,13 @@
     Tuple,
     Iterator,
     Text,
+    overload,
     TYPE_CHECKING,
 )
 
 import numpy as np
 from sortedcontainers import SortedDict
+from typing_extensions import Literal
 
 from . import (
     PYANNOTE_SEGMENT,
@@ -136,7 +138,17 @@
 from .timeline import Timeline
 from .feature import SlidingWindowFeature
 from .utils.generators import string_generator, int_generator
-from .utils.types import Label, Key, Support, LabelGenerator, TrackName, CropMode
+from .utils.types import (
+    Label,
+    Key,
+    Support,
+    LabelGenerator,
+    TrackName,
+    Track,
+    LabeledTrack,
+    TrackIterator,
+    CropMode,
+)
 
 if TYPE_CHECKING:
     import pandas as pd
@@ -259,9 +271,14 @@ def itersegments(self):
         """
         return iter(self._tracks)
 
-    def itertracks(
-        self, yield_label: bool = False
-    ) -> Iterator[Union[Tuple[Segment, TrackName], Tuple[Segment, TrackName, Label]]]:
+    @overload
+    def itertracks(self, yield_label: Literal[False] = ...) -> Iterator[Track]: ...
+    @overload
+    def itertracks(self, yield_label: Literal[True]) -> Iterator[LabeledTrack]: ...
+    @overload
+    def itertracks(self, yield_label: bool) -> TrackIterator: ...
+
+    def itertracks(self, yield_label: bool = False) -> TrackIterator:
         """Iterate over tracks (in chronological order)
 
         Parameters

pyannote/core/utils/types.py

@@ -13,6 +13,9 @@
 LabelGeneratorMode = Literal['int', 'string']
 LabelGenerator = Union[LabelGeneratorMode, Iterator[Label]]
 TrackName = Union[str, int]
+Track = Tuple['Segment', TrackName]
+LabeledTrack = Tuple['Segment', TrackName, Label]
+TrackIterator = Union[Iterator[Track], Iterator[LabeledTrack]]
 Key = Union['Segment', Tuple['Segment', TrackName]]
 Resource = Union['Segment', 'Timeline', 'SlidingWindowFeature',
                  'Annotation']