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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 _si(number):
 """Format a number using base-2 SI prefixes"""

    prefixes = ['', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y']
    while number > 1024:
        number /= 1024.0
        prefixes.pop(0)
    return '%0.2f%s' % (number, prefixes.pop(0))