code: def create_unique_base26_symlink(path, source):
      
      retries = 0
  
      while True:
          # if a link already exists that points at `source`, return it
          name = find_matching_symlink(path, source)
          if name:
              return os.path.join(path, name)
  
          # get highest current symlink in path
          names = [
              x for x in os.listdir(path)
              if os.path.islink(os.path.join(path, x))
          ]
  
          if names:
              prev = max(names)
          else:
              prev = None
  
          linkname = get_next_base26(prev)
          linkpath = os.path.join(path, linkname)
  
          # attempt to create the symlink
          try:
              os.symlink(source, linkpath)
              return linkpath
  
          except OSError as e:
              if e.errno != errno.EEXIST:
                  raise
  
          # if we're here, the same named symlink was created in parallel
          # somewhere. Try again up to N times.
          #
          if retries > 10:
              raise RuntimeError(
                  "Variant shortlink not created - there was too much contention.")
          retries += 1
docs: Create a base-26 symlink in `path` pointing to `source`.
  
      If such a symlink already exists, it is returned. Note that there is a small
      chance that this function may create a new symlink when there is already one
      pointed at `source`.
  
      Assumes `path` only contains base26 symlinks.
  
      Returns:
          str: Path to created symlink.