'Processes a batch of values with the same type.
ProcessValues is called *once per value type* for each value type in
the flow/hunt results collection.
Args:
value_cls: Class identifying type of the values to be processed.
values_generator_fn: Function returning an iterable with values. Each
value is a GRRMessage wrapping a value of a value_cls type.
values_generator_fn may be called multiple times within
1 ProcessValues() call - for example, when multiple passes over
the data are required.'

def ProcessValues(self, value_cls, values_generator_fn):

    raise NotImplementedError()
