Traceback (most recent call last)

[paramsingh96-zz]

I am downloading Planet Labs images. But getting below error when i type:
python train/scripts/download_planetlabs.py 37.796105 -122.461349 --buffer 200 --image_type rapideye --dir ../../data/planetlab/images/
Output:

Traceback (most recent call last):
  File "train/scripts/download_planetlabs.py", line 17, in <module>
    raise Exception('PLANET_KEY environment variable not set!')
Exception: PLANET_KEY environment variable not set!

Please help me out.