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core/assets/vendor/tabbable/README.txt

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+Drupal core uses the UMD build of tabbable.
+To create this build:
+Navigate to the root directory of the tabbable library.
+
+Ensure that dependencies have been installed:
+```
+yarn install
+```
+
+Build files for production:
+```
+yarn build
+```
+
+This will create an index.umd.min.js file in dist/ that can be used in Drupal.