code: def ensure_unique(iterable, key=lambda x: x):
      """
      Wrap an iterable to raise a ValueError if non-unique values are encountered.
  
      >>> list(ensure_unique('abc'))
      ['a', 'b', 'c']
      >>> consume(ensure_unique('abca'))
      Traceback (most recent call last):
      ...
      ValueError: Duplicate element 'a' encountered.
      """
      seen = set()
      seen_add = seen.add
      for element in iterable:
          k = key(element)
          if k in seen:
              raise ValueError(
                  f"Duplicate element {element!r} encountered."
              )
          seen_add(k)
          yield element
  
label_desc: Use image node_id 1 for calling a global function with example usage: ensure_unique(iterable, key) without return types