def start_of_chunk(prev_tag, tag, prev_type, type_):
    """Checks if a chunk started between the previous and current word.

    Args:
        prev_tag: previous chunk tag.
        tag: current chunk tag.
        prev_type: previous type.
        type_: current type.

    Returns:
        chunk_start: boolean.
    """
    chunk_start = False
    if tag == 'B':
        chunk_start = True
    if tag == 'S':
        chunk_start = True
    if prev_tag == 'E' and tag == 'E':
        chunk_start = True
    if prev_tag == 'E' and tag == 'I':
        chunk_start = True
    if prev_tag == 'S' and tag == 'E':
        chunk_start = True
    if prev_tag == 'S' and tag == 'I':
        chunk_start = True
    if prev_tag == 'O' and tag == 'E':
        chunk_start = True
    if prev_tag == 'O' and tag == 'I':
        chunk_start = True
    if tag != 'O' and tag != '.' and prev_type != type_:
        chunk_start = True
    return chunk_start
