How can I import module at parent directory?
In following package, I want to use techniques module in main.py
I am using __all__ to ignore tests when import trade. 
trade/
    __init__.py
    htmlparser.py
    utils.py
    techniques.py
    tests/
        testdata.json
        main.py
__init__.py:
__all__ = ["techniques", "utils", "htmlparser"]
