completes incomplete BaseExpression.is_free() change

mathics/builtin/patterns.py

@@ -1340,19 +1340,19 @@ class _StopGeneratorBaseExpressionIsFree(StopGenerator):
     pass
 
 
-def is_free(expr, form, evaluation):
+def item_is_free(item, form, evaluation):
     # for vars, rest in form.match(self, {}, evaluation, fully=False):
     def yield_match(vars, rest):
         raise _StopGeneratorBaseExpressionIsFree(False)
         # return False
 
     try:
-        form.match(yield_match, expr, {}, evaluation, fully=False)
+        form.match(yield_match, item, {}, evaluation, fully=False)
     except _StopGeneratorBaseExpressionIsFree as exc:
         return exc.value
 
-    if expr.is_atom():
+    if item.is_atom():
         return True
     else:
-        return expr.head.is_free(form, evaluation) and all(
-            leaf.is_free(form, evaluation) for leaf in expr.leaves)
+        return item_is_free(item.head, form, evaluation) and all(
+            item_is_free(leaf, form, evaluation) for leaf in item.leaves)

mathics/core/expression.py

@@ -312,24 +312,8 @@ def format(self, evaluation, form):
         return result
 
     def is_free(self, form, evaluation):
-        from mathics.core.pattern import StopGenerator
-
-        class StopGenerator_BaseExpression_is_free(StopGenerator):
-            pass
-
-        # for vars, rest in form.match(self, {}, evaluation, fully=False):
-        def yield_match(vars, rest):
-            raise StopGenerator_BaseExpression_is_free(False)
-            # return False
-        try:
-            form.match(yield_match, self, {}, evaluation, fully=False)
-        except StopGenerator_BaseExpression_is_free as exc:
-            return exc.value
-        if self.is_atom():
-            return True
-        else:
-            return self.head.is_free(form, evaluation) and all(
-                leaf.is_free(form, evaluation) for leaf in self.leaves)
+        from mathics.builtin.patterns import item_is_free
+        return item_is_free(self, form, evaluation)
 
     def is_inexact(self):
         return self.get_precision() is not None