Addressed minor copilot concerns

Author: VisLab

hed/schema/__init__.py

@@ -30,6 +30,7 @@
 - :data:`HedKey` / :data:`HedSectionKey` — enumerations of schema attribute and
   section names used when querying schema entries.
 - :func:`get_hed_versions` — list versions available in the local cache.
+- :func:`get_hed_xml_version` — read the HED version string from an XML schema file on disk.
 - :func:`cache_xml_versions` — pre-populate the local cache from the HED GitHub
   releases.
 

hed/schema/hed_schema_entry.py

@@ -406,6 +406,7 @@ def _finalize_inherited_attributes(self):
         self.inherited_attributes = self.attributes.copy()
         for attribute in self._section.inheritable_attributes:
             value = self._check_inherited_attribute(attribute, return_value=True)
+            # None means "not found in the hierarchy"; attribute values themselves are never None.
             if value is not None:
                 self.inherited_attributes[attribute] = value
 

hed/schema/schema_io/schema2base.py

@@ -124,7 +124,12 @@ def _output_annotations(self, hed_schema):
         raise NotImplementedError("This needs to be defined in the subclass")
 
     def _output_extras(self, hed_schema):
-        raise NotImplementedError("This needs to be defined in the subclass")
+        """Optional hook for format-specific sections not covered by the standard traversal.
+
+        The base implementation is a deliberate no-op.  Subclasses that need to
+        emit additional content (e.g. the header-attributes sheet in TSV) override
+        this method; subclasses that have nothing extra can safely omit it.
+        """
 
     def _output_epilogue(self, epilogue):
         raise NotImplementedError("This needs to be defined in the subclass")

tests/models/test_hed_group.py

@@ -125,13 +125,19 @@ def test_shallow_copy_raises_copy_error(self):
             copy.copy(group)
 
     def test_deep_copy_succeeds(self):
-        """copy.deepcopy() (and .copy()) must work correctly despite _parent cycles."""
+        """copy.deepcopy() and .copy() must work correctly despite _parent back-references."""
         hed_string = HedString("(Tag1, Tag2)", self.hed_schema)
         group = hed_string.get_first_group()
+
         deep = copy.deepcopy(group)
         self.assertIsNot(deep, group)
         self.assertEqual(str(deep), str(group))
 
+        # .copy() is the documented public API for deep-copying a HedGroup
+        via_copy = group.copy()
+        self.assertIsNot(via_copy, group)
+        self.assertEqual(str(via_copy), str(group))
+
 
 if __name__ == "__main__":
     unittest.main()