In a clean environment running training fails if tensorboard is not installed e.g.
```
Traceback (most recent call last):
File "/home/josh/miniconda3/envs/ultralytics/lib/python3.7/site-packages/torch/utils/tensorboard/__init__.py", line 2, in <module>
from tensorboard.summary.writer.record_writer import RecordWriter # noqa F401
ModuleNotFoundError: No module named 'tensorboard'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "train.py", line 6, in <module>
from torch.utils.tensorboard import SummaryWriter
File "/home/josh/miniconda3/envs/ultralytics/lib/python3.7/site-packages/torch/utils/tensorboard/__init__.py", line 4, in <module>
raise ImportError('TensorBoard logging requires TensorBoard with Python summary writer installed. '
ImportError: TensorBoard logging requires TensorBoard with Python summary writer installed. This should be available in 1.14 or above.
```