How can an error be triggered if validation fails?

In Python, to initiate an error upon a failed check, the raise operator is used, which throws an exception. Usually, the check is performed using a conditional statement, and if the condition is not met, an exception with an error message is raised.

Example:

def check_positive(number):
    if number <= 0:
        raise ValueError("The number must be positive")
    return True

check_positive(-5)  # This will raise a ValueError

This approach helps control data correctness and interrupts execution upon errors.