Generate Email

Write a function to generate a user's email address. The function takes a user's name and domain as input strings, and outputs an email in the format 'name@domain'. Ensure that both the name and domain contain only alphanumeric characters. If any non-conforming characters are included, raise a ValueError indicating an invalid name or domain. For example, name: 'john', domain: 'example.com', the output should be john@example.com. Example Input john example.com