has_indicators()

has_indicators() takes two indicators and returns true. The None keyword is used as a wildcard to be any characters.

eg. counting the subjecting headings are Library of Congress (2nd indicator = 0)
```python
for record in reader:
    headings = record.get_fields('600', '610', '611', '630', '648', '650')
    
    for h in headings:
        answer = h.has_indicators(None, '0')
        if answer == True:
            true += 1
        else:
            false += 1
```