How to validate custom Flow screen components in Flows by Narender Singh

Narender Singh form https://forcepanda.wordpress.com posted a series of blogs on how to add validation to custom flow screen components:

Part 1 https://forcepanda.wordpress.com/2019/07/09/how-to-validate-custom-flow-screen-components-in-flows-part-1/

Part 2 https://forcepanda.wordpress.com/2019/07/11/retain-input-values-while-validating-custom-flow-screen-lightning-components-part-2/

Part 3 https://forcepanda.wordpress.com/2019/07/12/adding-validation-errors-on-individual-inputs-in-custom-flow-screen-components-part-3/