Get maximum width of progress bar

        :rtype: int
        :returns: Maximum column width of progress bar

def max_width(self):
        """Get maximum width of progress bar

        :rtype: int
        :returns: Maximum column width of progress bar
        """
        value, unit = float(self._width_str[:-1]), self._width_str[-1]

        ensure(unit in ["c", "%"], ValueError,
               "Width unit must be either 'c' or '%'")

        if unit == "c":
            ensure(value <= self.columns, ValueError,
                   "Terminal only has {} columns, cannot draw "
                   "bar of size {}.".format(self.columns, value))
            retval = value
        else:  # unit == "%"
            ensure(0 < value <= 100, ValueError,
                   "value=={} does not satisfy 0 < value <= 100".format(value))
            dec = value / 100
            retval = dec * self.columns

        return floor(retval)