Answers for "Module build failed: Error: Requires Babel "^7.0.0-0", but was loaded with "6.26.3"."

Error: Requires Babel "^7.0.0-0", but was loaded with "6.26.3". If

npm install --save-dev "babel-core@^7.0.0-bridge.0"

error: requires babel "^7.0.0-0", but was loaded with "6.26.3".

Looks like you need
to install babel-core as the docs 
suggest: https://jestjs.io/docs/en/getting-started#using-babel

yarn add --dev babel-jest babel-core@^7.0.0-bridge.0 @babel/core regenerator-runtime