def split_txts(txts):
    """
    Args:
        txts: The texts that will be split
              into single characters

    Returns:
        The splitted texts and array of all unique characters
        in those texts.

    """
    txts_splitted = []
    unique_chars = set()

    for txt in txts:
        splitted = list(txt)
        splitted = [ch if ch != ' ' else '<SPACE>' for ch in splitted]
        txts_splitted.append(splitted)
        unique_chars.update(splitted)
    return txts_splitted, sorted(unique_chars)