func args should be None to work correctly with configure()
WIP
json_encoding_default for datetimes; debug output; dont double extend container if flush=False
unicode typecast fix
correctly handle clearing proxy from config when passing to container(**config)
test fixes
test fixes; convert nulls -> None
pep8 and logging fix
optimazations; use copy instead of deepcopy
added helper is_defined; cleaned up useless use of partial; fixed bug in _add_variants (loop assignement)
use is_defined, not is_true; fix add variants bug