TODO

5010
Repeating elements, composites
Syntax on composites
999

Python 3
    Overriding __eq__ blocks inheritance of __hash__
    raise Exception*(*args)
    except SomeException as e
    e.__traceback__ replaces sys.exc_info()
    next() -> __next__()

Context
    yield an object (maybe X12DataNode)
    filter
    query sub-loops - tree iteration
    handle error returns - throw events?
    node.select('//path'): get all matching sub-loops

x12file:
    check invalid seg term (004)
    check invalid ele term (026)

Path/property local overrides

TA1 input

LX index incrementing

For large input files, split html output into parts

Error Handling
    Remove errh object from map_if, map_walker. Return errors as list

Unit Testing
    x12file - HL counting?
    HL reset bug