Fix type error in flat-map

Author: dbrattli

.pre-commit-config.yaml

@@ -26,7 +26,7 @@ repos:
         language: node
         pass_filenames: false
         types: [python]
-        additional_dependencies: ["pyright@1.1.227"]
+        additional_dependencies: ["pyright@1.1.228"]
     repo: local
   - hooks:
       - id: mypy

reactivex/internal/concurrency.py

@@ -1,10 +1,10 @@
 from threading import RLock, Thread
 from typing import Any, Callable, TypeVar
+
 from typing_extensions import ParamSpec
 
 from reactivex.typing import StartableTarget
 
-
 _T = TypeVar("_T")
 _P = ParamSpec("_P")
 

reactivex/internal/utils.py

@@ -1,7 +1,9 @@
 from functools import update_wrapper
 from types import FunctionType
 from typing import TYPE_CHECKING, Any, Callable, Iterable, Optional, TypeVar, cast
+
 from typing_extensions import ParamSpec
+
 from reactivex import abc
 from reactivex.disposable import CompositeDisposable
 from reactivex.disposable.refcountdisposable import RefCountDisposable
@@ -38,7 +40,7 @@ def alias(name: str, doc: str, fun: Callable[_P, _T]) -> Callable[_P, _T]:
     _fun = cast(FunctionType, fun)
     args = (_fun.__code__, _fun.__globals__)
     kwargs = {"name": name, "argdefs": _fun.__defaults__, "closure": _fun.__closure__}
-    alias_ = FunctionType(*args, **kwargs)
+    alias_ = FunctionType(*args, **kwargs)  # type: ignore
     alias_ = update_wrapper(alias_, _fun)
     alias_.__kwdefaults__ = _fun.__kwdefaults__
     alias_.__doc__ = doc

reactivex/operators/_flatmap.py

@@ -1,8 +1,9 @@
 from asyncio import Future
-from typing import Any, Callable, Iterable, Optional, TypeVar, Union, cast
+from typing import Any, Callable, Optional, TypeVar, Union, cast
 
 from reactivex import Observable, from_, from_future
 from reactivex import operators as ops
+from reactivex.internal.basic import identity
 from reactivex.typing import Mapper, MapperIndexed
 
 _T1 = TypeVar("_T1")
@@ -14,14 +15,16 @@ def _flat_map_internal(
     mapper: Optional[Mapper[_T1, Any]] = None,
     mapper_indexed: Optional[MapperIndexed[_T1, Any]] = None,
 ) -> Observable[Any]:
-    def projection(x: _T1, i: int):
-        mapper_result = (
-            mapper(x) if mapper else mapper_indexed(x, i) if mapper_indexed else None
+    def projection(x: _T1, i: int) -> Observable[Any]:
+        mapper_result: Any = (
+            mapper(x)
+            if mapper
+            else mapper_indexed(x, i)
+            if mapper_indexed
+            else identity
         )
         if isinstance(mapper_result, Future):
             result: Observable[Any] = from_future(cast("Future[Any]", mapper_result))
-        elif isinstance(mapper_result, Iterable):
-            result = from_(mapper_result)
         elif isinstance(mapper_result, Observable):
             result = mapper_result
         else: