Remove TypeAlias for Python 3.9

Author: enwask

devito/ir/iet/visitors.py

@@ -7,7 +7,7 @@
 from collections import OrderedDict
 from collections.abc import Callable, Iterable, Iterator, Sequence
 from itertools import chain, groupby
-from typing import Any, Generic, TypeAlias, TypeVar
+from typing import Any, Generic, TypeVar
 import ctypes
 
 import cgen as c
@@ -1046,7 +1046,7 @@ def _defines_aliases(n):
             else:
                 yield i
 
-    RulesDict: TypeAlias = dict[str, Callable[[Node], Iterator[Any]]]
+    RulesDict = dict[str, Callable[[Node], Iterator[Any]]]
     rules: RulesDict = {
         'symbolics': lambda n: n.functions,
         'basics': lambda n: (i for i in n.expr_symbols if isinstance(i, Basic)),
@@ -1108,7 +1108,7 @@ class FindNodes(LazyVisitor[list[Node]]):
                      appears.
     """
 
-    RulesDict: TypeAlias = dict[str, Callable[[type, Node], bool]]
+    RulesDict = dict[str, Callable[[type, Node], bool]]
     rules: RulesDict = {
         'type': lambda match, o: isinstance(o, match),
         'scope': lambda match, o: match in flatten(o.children)