code: def sha256sum(file):
      block_size = 16 * 1024 * 1024  # 16 MB block size
      b = bytearray(block_size)
      file_hash = hashlib.sha256()
      mv = memoryview(b)
      with open(file, "rb", buffering=0) as f:
          while True:
              n = f.readinto(mv)
              if not n:
                  break
              file_hash.update(mv[:n])
  
      return file_hash.hexdigest()
  
label_desc: Use image node_id 1 for calling a global function with example usage: sha256sum(file) and returns: file_hash