'Verifies this filter set can process the result data.'

def Validate(self):

    bad_filters = []
    for f in self.filters:
        try:
            f.Validate()
        except DefinitionError as e:
            bad_filters.append(('%s:    %s' % (f.expression, e)))
    if bad_filters:
        raise DefinitionError(('Filters    with    invalid    expressions:    %s' % ',    '.join(bad_filters)))
