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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 _sounds_re(include_erhua=False):
 """Sounds are syllables + tones"""


    tone = '[1-5]'
    optional_final_erhua = '|r\\b' if include_erhua else ''
    pattern = '({}{}{})'.format(_joined_syllables_re(), tone, optional_final_erhua)
    return re.compile(pattern, re.IGNORECASE)