user input validation function added with all sort of testing

[Limyangtyin]

Type of change

• Added new project
• Bug fix
• [O] New features
• [O] Enhanced documentation

Changes proposed in this pull request

• Project name :

Calendar

• Short description :

I have added user validation function to check for user input. Included all sort of testing and documentation.

Checklist

• [ O] The code is Python 3 compatible
• [ O] I have added relevant comments in my file to make code understandable
• [ O] I have added my project in a folder which includes all the necessary files

[github-actions]

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[Mrinank-Bhowmick]

Please maintain project directory structure