Assertion

 If we want to validate something then we can put assertion.

assert 0 <= price <= product['price']

If assertion condition doesn't satisfy, we'll get assertion error.

Problem with the assertion is that our code can fail in the Production and stop working

* assertion cant be in the tuple

assert(1 == 2, 'This should fail')

This condition is always True so you'll never get an assertion error.

* Correct Statement:

assert 1==2, ('this condition is not true')