Remove conditional code for Python versions less than 3.9 (#442)

This patch removes some conditional branches that were set up to support
Python 3.8. Now that we have gotten rid of Python 3.8 support these can
be removed.

Fixes #38.

compiler_opt/distributed/worker.py

@@ -15,7 +15,6 @@
 """Common abstraction for a worker contract."""
 
 import abc
-import sys
 from typing import Any, List, Iterable, Optional, Protocol, TypeVar
 
 import gin
@@ -104,8 +103,4 @@ def get_full_worker_args(worker_class: 'type[Worker]', **current_kwargs):
     # we don't have a way to check if `worker_class` is even known to gin, and
     # it's not a requirement that it were. Tests, for instance, don't use gin.
     pass
-  # Issue #38
-  if sys.version_info >= (3, 9):
-    return current_kwargs | gin_config
-  else:
-    return {**current_kwargs, **gin_config}
+  return current_kwargs | gin_config

compiler_opt/rl/data_collector_test.py

@@ -15,7 +15,6 @@
 """Tests for data_collector."""
 
 # pylint: disable=protected-access
-import sys
 from unittest import mock
 
 from absl.testing import absltest
@@ -29,11 +28,7 @@ def test_build_distribution_monitor(self):
     data = [3, 2, 1]
     monitor_dict = data_collector.build_distribution_monitor(data)
     reference_dict = {'mean': 2, 'p_0.1': 1}
-    # Issue #38
-    if sys.version_info >= (3, 9):
-      self.assertEqual(monitor_dict, monitor_dict | reference_dict)
-    else:
-      self.assertEqual(monitor_dict, {**monitor_dict, **reference_dict})
+    self.assertEqual(monitor_dict, monitor_dict | reference_dict)
 
   @mock.patch('time.time')
   def test_early_exit(self, mock_time):

compiler_opt/rl/local_data_collector_test.py

@@ -17,7 +17,6 @@
 # pylint: disable=protected-access
 import collections
 import string
-import sys
 from typing import List, Tuple
 
 import tensorflow as tf
@@ -180,15 +179,8 @@ def _test_iterator_fn(data_list):
               'total_trajectory_length': 18,
           }
       }
-      # Issue #38
-      if sys.version_info >= (3, 9):
-        self.assertEqual(monitor_dict,
-                         monitor_dict | expected_monitor_dict_subset)
-      else:
-        self.assertEqual(monitor_dict, {
-            **monitor_dict,
-            **expected_monitor_dict_subset
-        })
+      self.assertEqual(monitor_dict,
+                       monitor_dict | expected_monitor_dict_subset)
       data_iterator, monitor_dict = collector.collect_data(
           policy=_mock_policy, model_id=0)
       data = list(data_iterator)
@@ -200,15 +192,8 @@ def _test_iterator_fn(data_list):
               'total_trajectory_length': 18,
           }
       }
-      # Issue #38
-      if sys.version_info >= (3, 9):
-        self.assertEqual(monitor_dict,
-                         monitor_dict | expected_monitor_dict_subset)
-      else:
-        self.assertEqual(monitor_dict, {
-            **monitor_dict,
-            **expected_monitor_dict_subset
-        })
+      self.assertEqual(monitor_dict,
+                       monitor_dict | expected_monitor_dict_subset)
 
       collector.close_pool()