Add a few tests to bring up coverage of argextract up to 100%.
Add a few nocoverage pragmas for pypy dependent code.
No coverage for Python 3 compat code.
No coverage pragma for NotImplementedError.
Bring predicate coverage up to 100% by testing for single predicate
fallback not found.
Whitespace.
No coverage for the repr.
Complete bring up the test coverage back to 100%.