I have the following syntax in a gitlab-ci.yml file.
what is the meaning of &default in this
.default:
  only: &default
    - master
    - dev
    - merge_requests
........
code-check:
  stage: lint
  script:
    - pip install black
    - black .
    - black --check .
    - black --include \.pyi?$ .
    - black --exclude \.git\.venv .
    - black --line-length 88 .
  allow_failure: true
  only: *default
