The Pascal VOC challenge is a very popular dataset however, the website frequently goes down. 
In case you are unable to download the VOCtrainval_11-May-2012.tar within the Dockerfile or Singularity file,
please uncomment:
`#url = 'https://drive.google.com/file/d/1YkakD_qJuKmwAZF_HwLGLNb8fcqZbtx7/view?usp=sharing'`  
in /source_code/dataset.py code.