No module named `gflags`

[austinleedavis]

python train_mineral_shards.py generates the following error:

Traceback (most recent call last):
  File "train_mineral_shards.py", line 3, in <module>
    import gflags as flags
ModuleNotFoundError: No module named 'gflags'

[agsnyder]

I got past this by changing it to:
from absl import flags

Seems that gflags is deprecated, and if you look at the code from chris-chris that this code is based on, that is what they went to.