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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 _parse_date_input(date_input, default_offset=0):
 """Parses a date input."""

    if date_input:
        try:
            return parse_date_input(date_input)
        except ValueError as err:
            raise CommandError(force_text(err))
    else:
        return get_midnight() - timedelta(days=default_offset)