def extract_symbols(lst):
    """Takes a row or column of idents or alphanumeric symbols and just
    extracts the symbols (letters).

    Args:
        lst (list): list of strings representing the cells in a row or col
            e.g. ['1a', '1b', '1c', 2, 2]

    Returns:
        (list): just the letters from the input
            e.g. ['a', 'b', 'c']
    """
    return [char
            for item in lst if isinstance(item, str)
            for char in item if not char.isdigit()]