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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 validate_dtype_freq(dtype, freq):
 """ If both a dtype and a freq are available, ensure they match. If only dtype is available, extract the implied freq. Parameters dtype : dtype freq : DateOffset or None Returns ------- freq : DateOffset Raises ------ ValueError : non-period dtype IncompatibleFrequency : mismatch between dtype and freq """

    if freq is not None:
        freq = frequencies.to_offset(freq)

    if dtype is not None:
        dtype = pandas_dtype(dtype)
        if not is_period_dtype(dtype):
            raise ValueError('dtype must be PeriodDtype')
        if freq is None:
            freq = dtype.freq
        elif freq != dtype.freq:
            raise IncompatibleFrequency('specified freq and dtype '
                                        'are different')
    return freq