def remove_non_latin(input_string, also_keep=None):
    """Remove non-Latin characters.
    `also_keep` should be a list which will add chars (e.g. punctuation)
    that will not be filtered.
    """
    if also_keep:
        also_keep += [' ']
    else:
        also_keep = [' ']
    latin_chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    latin_chars += latin_chars.lower()
    latin_chars += ''.join(also_keep)
    no_latin = "".join([char for char in input_string if char in latin_chars])
    return no_latin