missing function creation specialization

Author: cosminbasca

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/BuiltinConstructors.java

@@ -2184,6 +2184,12 @@ public PFunction function(LazyPythonClass cls, PCode code, PDict globals, @Suppr
             return factory().createFunction("<lambda>", getTypeName(cls), code, globals, getClosure(getObjectArrayNode.execute(closure)));
         }
 
+        @Specialization
+        public PFunction function(LazyPythonClass cls, PCode code, PDict globals, @SuppressWarnings("unused") PNone name, @SuppressWarnings("unused") PNone defaultArgs, @SuppressWarnings("unused") PNone closure,
+                        @Shared("getObjectArrayNode") @Cached GetObjectArrayNode getObjectArrayNode) {
+            return factory().createFunction("<lambda>", getTypeName(cls), code, globals, null);
+        }
+
         @Specialization
         public PFunction function(LazyPythonClass cls, PCode code, PDict globals, String name, @SuppressWarnings("unused") PNone defaultArgs, PTuple closure,
                         @Shared("getObjectArrayNode") @Cached GetObjectArrayNode getObjectArrayNode) {