<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def reduce(cls, requirements: Iterable['FetchRequirement']) \ -> 'FetchRequirement': """Reduce a set of fetch requirements into a single requirement. Args: requirements: The set of fetch requirements. """

        return reduce(lambda x, y: x | y, requirements, cls.NONE)