code: def _dedup(items, insensitive):
      '''
      Deduplicate an item list, and preserve order.
  
      For case-insensitive lists, drop items if they case-insensitively match
      a prior item.
      '''
      deduped = []
      if insensitive:
          i_deduped = []
          for item in items:
              lowered = item.lower()
              if lowered not in i_deduped:
                  deduped.append(item)
                  i_deduped.append(lowered)
      else:
          for item in items:
              if item not in deduped:
                  deduped.append(item)
      return dedupef _dedup(items, insensitive):
      '''
      Deduplicate an item list, and preserve order.
  
      For case-insensitive lists, drop items if they case-insensitively match
      a prior item.
      '''
      deduped = []
      if insensitive:
          i_deduped = []
          for item in items:
              lowered = item.lower()
              if lowered not in i_deduped:
                  deduped.append(item)
                  i_deduped.append(lowered)
      else:
          for item in items:
              if item not in deduped:
                  deduped.append(item)
      return deduped
docs: Deduplicate an item list, and preserve order.
  
      For case-insensitive lists, drop items if they case-insensitively match
      a prior item.