<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def check_if_numbers_are_consecutive(list_):
 """ Returns True if numbers in the list are consecutive :param list_: list of integers :return: Boolean """

    return all((True if second - first == 1 else False
                for first, second in zip(list_[:-1], list_[1:])))