chore: import upstream snapshot with attribution

Algorithm.Python/BasicTemplateTradableIndexAlgorithm.py

@@ -0,0 +1,30 @@
+# QUANTCONNECT.COM - Democratizing Finance, Empowering Individuals.
+# Lean Algorithmic Trading Engine v2.0. Copyright 2014 QuantConnect Corporation.
+#
+# 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
+
+from AlgorithmImports import *
+from BasicTemplateIndexAlgorithm import BasicTemplateIndexAlgorithm
+
+class BasicTemplateTradableIndexAlgorithm(BasicTemplateIndexAlgorithm):
+    ticket: OrderTicket | None = None
+    def initialize(self) -> None:
+        super().initialize()
+        self.securities[self.spx].is_tradable = True
+        
+    def on_data(self, data: Slice):
+        super().on_data(data)
+        if not self.ticket:
+            self.ticket = self.market_order(self.spx, 1)
+
+    def on_end_of_algorithm(self) -> None:
+        if self.ticket and self.ticket.status != OrderStatus.FILLED:
+            raise AssertionError("Index is tradable.")