7. yarn check 
yarn check  Verifies that versions of the package dependencies in the current project’s package.json match those in yarn’s lock file. NOTE: The command yarn check has been historically buggy and undermaintained and, as such, has been deprecated and will be removed in Yarn 2.0. You should use yarn install --check-files instead. The switches --integrity and --verify-tree are mutually exclusive. 
yarn check --integrity  Verifies that versions and hashed values of the package contents in the project’s package.json match those in yarn’s lock file. This helps to verify that the package dependencies have not been altered. 
yarn check --verify-tree  Recursively verifies that the dependencies in package.json are present in node_modules and have the right version. This check does not consider yarn.lock.

    
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