[unlikely to implement] Serialization helper

[nottombrown]

Follow up to #4

If serialization of the args becomes annoying (for example, if researchers frequently try to serialize strings have characters that bash mis-interprets), we could let the user set flags within their executable function also. I think that we likely don't need to do this though.

# train.py
def main():
  ...

if __name__ == '__main__':
  FLAGS = argparser.parse()
  berg.setup_flags(FLAGS)
  main()

My current thinking is that this is more trouble than it is worth, and that serializing through CLI flags yields code that is easier to understand and more portable than this proposal.