For this line (in Python 2.7.10):
from tensorboardX import SummaryWriter

I am getting this error:
ModuleNotFoundError: No module named 'tensorboardX'

I installed:
$ pip install tensorboardX
and the result for pip list|grep tensor:
tensorboard          1.13.1         
tensorboardX         1.7            
tensorflow           1.13.1         
tensorflow-estimator 1.13.0

Any ideas how can I solve this error?