Let's say you've created a registration form for people wanting to take part in your online book club. In order to send them invitations, you need to know their email address, so you are writing a program to check whether the field "email" is filled correctly.
Write a function that takes a string and checks that a user's email meets the following conditions:
- it doesn't contain spaces,
- it contains the @ symbol,
- after @, there's a dot, but in a correct address a dot shouldn't stand immediately after @,
(@. should not be in the string).
Note that dots may also occur before @!
The function should return True if all of the conditions are true, and False otherwise.
You are not supposed to handle input or call your function, just implement it.
