code: def where_is(strings, pattern, n=1, lookup_func=re.match):
      
      count = 0
      for idx, item in enumerate(strings):
          if lookup_func(pattern, item):
              count += 1
              if count == n:
                  return idx
      return -1
docs: Return index of the nth match found of pattern in strings
  
      Parameters
      ----------
      strings: list of str
          List of strings
  
      pattern: str
          Pattern to be matched
  
      nth: int
          Number of times the match must happen to return the item index.
  
      lookup_func: callable
          Function to match each item in strings to the pattern, e.g., re.match or re.search.
  
      Returns
      -------
      index: int
          Index of the nth item that matches the pattern.
          If there are no n matches will return -1