Add support for subscript setitem

trans/transpiler/phases/typing/block.py

@@ -96,8 +96,17 @@ class ScoperBlockVisitor(ScoperVisitor):
             attr_type = self.expr().visit(target)
             attr_type.unify(decl_val)
             return False
+        elif isinstance(target, ast.Subscript):
+            expr = self.expr()
+            left = expr.visit(target.value)
+            args = target.slice if type(target.slice) == tuple else [target.slice]
+            args = [expr.visit(e) for e in args]
+            if len(args) == 1:
+                args = args[0]
+            expr.make_dunder([left, args, decl_val], "setitem")
+            return False
         else:
-            raise NotImplementedError(target)
+            raise NotImplementedError(ast.unparse(target))
 
     def visit_FunctionDef(self, node: ast.FunctionDef):
         argtypes = [self.visit_annotation(arg.annotation) for arg in node.args.args]