code: def sha256sum(path, blocksize=65536):
      
      sig = hashlib.sha256()
      with open(path, 'rb') as f:
          buf = f.read(blocksize)
          while len(buf) > 0:
              sig.update(buf)
              buf = f.read(blocksize)
      return sig.hexdigest()
docs: Computes the SHA256 signature of a file to verify that the file has not
      been modified in transit and that it is the correct version of the data.