code: def sha256sum(path, blocksize=65536):
      """
      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.
      """
      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()
  
label_desc: Use image node_id 1 for calling a global function with example usage: sha256sum(path, blocksize) and returns: sig