PEP 690: Add flexibility to set_eager_imports() (#2571)

This adds a callback to the proposed `importlib.set_eager_imports()`.

Co-authored-by: Carl Meyer <carl@oddbird.net>

pep-0690.rst

@@ -231,6 +231,17 @@ a list of module names within which all imports will be eager::
 The effect of this is also shallow: all imports within ``one.mod`` will be
 eager, but not imports in all modules imported by ``one.mod``.
 
+``set_eager_imports()`` can also take a callback which receives a module name and returns
+whether imports within this module should be eager::
+
+    import re
+    from importlib import set_eager_imports
+    
+    def eager_imports(name):
+        return re.match(r"foo\.[^.]+\.logger", name)
+
+    set_eager_imports(eager_imports)
+
 
 Backwards Compatibility
 =======================