code: def gen_unused_symbols(used: str, n: int) -> Iterator[str]:
      """Generate ``n`` symbols that are not already in ``used``.
  
      **Examples:**
      ```python
      list(oe.parser.gen_unused_symbols("abd", 2))
      #> ['c', 'e']
      ```
      """
      i = cnt = 0
      while cnt < n:
          s = get_symbol(i)
          i += 1
          if s in used:
              continue
          yield s
          cnt += 1
  
file_path: ivy/ivy/utils/einsum_parser.py
imports: import itertools
  from typing import Any, Dict, Iterator, List, Tuple, Union
  import numpy
label_desc: Use image node_id 4 for calling a global function with example usage: gen_unused_symbols(used, n) without return types