chore: add licence

quafu/elements/oracle.py

@@ -1,3 +1,17 @@
+#  (C) Copyright 2023 Beijing Academy of Quantum Information Sciences
+#
+#  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 abc import ABCMeta
 from quafu.elements import QuantumGate, Instruction
 from typing import Dict, Iterable, List