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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 _first_line_re():
 """ Return a regular expression based on first_line_re suitable for matching strings. """

    if isinstance(first_line_re.pattern, str):
        return first_line_re

    # first_line_re in Python >=3.1.4 and >=3.2.1 is a bytes pattern.
    return re.compile(first_line_re.pattern.decode())