Future bright future will you satisfy mypy?

Author: pavoljuhas

cirq-core/cirq/vis/heatmap.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 import copy
 from dataclasses import astuple, dataclass
 from typing import (