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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 _check_header(channel_file, s_freq):
 """For each file, make sure that the header is consistent with the information in the text file. Parameters channel_file : Path path to single filename with the header s_freq : int sampling frequency Returns ------- int gain from digital to microvolts (the same information is stored in the Continuous_Data.openephys but I trust the header for each file more. """

    hdr = _read_header(channel_file)

    assert int(hdr['header_bytes']) == HDR_LENGTH
    assert int(hdr['blockLength']) == BLK_LENGTH
    assert int(hdr['sampleRate']) == s_freq

    return float(hdr['bitVolts'])