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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 zfill(self, width):
 """Pad a numeric string with zeros on the left, to fill a field of the specified width. The string is never truncated. :param int width: Length of output string. """

        if not self.value_no_colors:
            result = self.value_no_colors.zfill(width)
        else:
            result = self.value_colors.replace(self.value_no_colors, self.value_no_colors.zfill(width))
        return self.__class__(result, keep_tags=True)