Allow PEP 448 **expr syntax in dict literals

python/psi-api/src/com/jetbrains/python/psi/PyDoubleStarExpression.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2000-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.jetbrains.python.psi;
+
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author vlan
+ */
+public interface PyDoubleStarExpression extends PyExpression {
+  @Nullable
+  PyExpression getExpression();
+}

python/psi-api/src/com/jetbrains/python/psi/PyElementVisitor.java

@@ -237,6 +237,10 @@ public class PyElementVisitor extends PsiElementVisitor {
     visitPyExpression(node);
   }
 
+  public void visitPyDoubleStarExpression(PyDoubleStarExpression node) {
+    visitPyExpression(node);
+  }
+
   public void visitPySubscriptionExpression(PySubscriptionExpression node) {
     visitPyExpression(node);
   }