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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def split_taf(txt: str) -> [str]: # type: ignore """ Splits a TAF report into each distinct time period """

    lines = []
    split = txt.split()
    last_index = 0
    for i, item in enumerate(split):
        if starts_new_line(item) and i != 0 and not split[i - 1].startswith('PROB'):
            lines.append(' '.join(split[last_index:i]))
            last_index = i
    lines.append(' '.join(split[last_index:]))
    return lines