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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 get_available_channels(header):
 """Get the available channels from the header information"""


    chlist_str = header['15_SECONDARY_PRODUCT_HEADER'][
        'SelectedBandIDs']['Value']
    retv = {}

    for idx, char in zip(range(12), chlist_str):
        retv[CHANNEL_NAMES[idx + 1]] = (char == 'X')

    return retv