it seems was impossible syntax in Python 3.9

9d4fa10b · Durman · 7b5548c8 · 9d4fa10b
--- a/core/socket_conversions.py
+++ b/core/socket_conversions.py
@@ -216,16 +216,16 @@ class DefaultImplicitConversionPolicy(NoImplicitConversionPolicy):
            return is_ultimately(source_data, expected_type)


-class FieldImplicitConversionPolicy(DefaultImplicitConversionPolicy):
+def check_nesting_level(func):
+    def the_check(source_data):
+        level = get_data_nesting_level(source_data)
+        if level > 2:
+            raise TypeError("Too high data nesting level for Number -> Scalar Field conversion: %s" % level)
+        return func(source_data)
+    return the_check
+

-    @staticmethod
-    def check_nesting_level(func):
-        def the_check(source_data):
-            level = get_data_nesting_level(source_data)
-            if level > 2:
-                raise TypeError("Too high data nesting level for Number -> Scalar Field conversion: %s" % level)
-            return func(source_data)
-        return the_check
+class FieldImplicitConversionPolicy(DefaultImplicitConversionPolicy):

    default_conversions = {
        ('SvMatrixSocket', 'SvVectorFieldSocket'): matrices_to_vfield,