docs: def read_apply(lib, symbol, func, chunk_range=None):
      """
      Apply `func` to each chunk in lib.symbol
  
      Parameters
      ----------
      lib: arctic library
      symbol: str
          the symbol for the given item in the DB
      chunk_range: None, or a range object
          allows you to subset the chunks by range
  
      Returns
      -------
      generator
      """
      for chunk in lib.iterator(symbol, chunk_range=chunk_range):
          yield func(chunk)