Constants 'zero' and 'non-zero' are not handled

[x44]

I'm not sure if this is a bug.
condition_parser.py _get_const_value() returns (None, '') if the value is 'zero' or 'non-zero'.
Therefore, conditions such as
Number of Blocks (300A,00F0) is non-zero.
Number of Beams (300A,0080) is greater than zero.
are silently ignored.

In iod_validator.py _tag_matches() there is a TODO which could have something to do with this issue.

[mrbean-bremen]

Yes, you are right, thank you! I'm going to fix this (up to a point, more complicated expressions will still be ignored).