add __all__ and fix flake8 issues

Author: basnijholt

adaptive/__init__.py

@@ -4,17 +4,52 @@
 
 from adaptive import learner, runner, utils
 from adaptive._version import __version__
-from adaptive.learner import (AverageLearner, BalancingLearner, BaseLearner,
-                              DataSaver, IntegratorLearner, Learner1D,
-                              Learner2D, LearnerND, make_datasaver)
-from adaptive.notebook_integration import (active_plotting_tasks, live_plot,
-                                           notebook_extension)
+from adaptive.learner import (
+    AverageLearner,
+    BalancingLearner,
+    BaseLearner,
+    DataSaver,
+    IntegratorLearner,
+    Learner1D,
+    Learner2D,
+    LearnerND,
+    make_datasaver,
+)
+from adaptive.notebook_integration import (
+    active_plotting_tasks,
+    live_plot,
+    notebook_extension,
+)
 from adaptive.runner import AsyncRunner, BlockingRunner, Runner
 
+__all__ = [
+    "learner",
+    "runner",
+    "utils",
+    "__version__",
+    "AverageLearner",
+    "BalancingLearner",
+    "BaseLearner",
+    "DataSaver",
+    "IntegratorLearner",
+    "Learner1D",
+    "Learner2D",
+    "LearnerND",
+    "make_datasaver",
+    "active_plotting_tasks",
+    "live_plot",
+    "notebook_extension",
+    "AsyncRunner",
+    "BlockingRunner",
+    "Runner",
+]
+
 with suppress(ImportError):
     # Only available if 'scikit-optimize' is installed
-    from adaptive.learner import SKOptLearner
+    from adaptive.learner import SKOptLearner  # noqa: F401
 
+    __all__.append("SKOptLearner")
 
-del _version
-del notebook_integration  # to avoid confusion with `notebook_extension`
+# to avoid confusion with `notebook_extension` and `__version__`
+del _version  # noqa: F821
+del notebook_integration  # noqa: F821

adaptive/learner/__init__.py

@@ -11,6 +11,20 @@
 from adaptive.learner.learner2D import Learner2D
 from adaptive.learner.learnerND import LearnerND
 
+__all__ = [
+    "AverageLearner",
+    "BalancingLearner",
+    "BaseLearner",
+    "DataSaver",
+    "make_datasaver",
+    "IntegratorLearner",
+    "Learner1D",
+    "Learner2D",
+    "LearnerND",
+]
+
 with suppress(ImportError):
     # Only available if 'scikit-optimize' is installed
-    from adaptive.learner.skopt_learner import SKOptLearner
+    from adaptive.learner.skopt_learner import SKOptLearner  # noqa: F401
+
+    __all__.append("SKOptLearner")