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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 _bin_zfill(num, width=None):
 """Convert a base-10 number to a binary string. Parameters num: int width: int, optional Zero-extend the string to this width. Examples -------- '101010' '00101010' """

    s = bin(num)[2:]
    return s if width is None else s.zfill(width)