Add type checking.

.gitlab-ci.yml

@@ -33,6 +33,13 @@ Autoformatting:
   - pip install black
   - black --check --verbose --diff --color .
 
+Typechecker:
+  stage: linting
+  script:
+  - pip install mypy
+  - mypy --ignore-missing-imports --strict plotid tests examples
+  - allow_failure: true
+
 test:
   stage: testing
   tags: