'should allow other aggregating/mod use in filter_fn
Although, it would be better to subclass and override assemble_current_block'

def test_hack_block_filter_fn(self):

    def is_not_indented(line):
        strip_diff = (len(line) - len(line.lstrip()))
        return (strip_diff == 0)
    def empty_block(block):
        if (len(block) <= 1):
            return None
        return {'header': block[0].strip(), 'data': [b.strip() for b in block[1:] if b.strip()]}
    (contents, provider, data) = self.contents_provider_and_data(strip_lines=False, strip_newlines=True, new_block_delim_fn=is_not_indented, block_filter_fn=empty_block)
    self.assertEqual(data, [{'header': 'One', 'data': ['ABCD']}, {'header': 'Two', 'data': ['ABCD', 'EFGH']}])
    self.assertCounters(provider, 3, 2, 2)
