Build format string from a format specification.

        :param format_spec:     Format specification (as FormatSpec object).
        :return: Composed format (as string).

def make_format(format_spec):
        """Build format string from a format specification.

        :param format_spec:     Format specification (as FormatSpec object).
        :return: Composed format (as string).
        """
        fill = ''
        align = ''
        zero = ''
        width = format_spec.width
        if format_spec.align:
            align = format_spec.align[0]
            if format_spec.fill:
                fill = format_spec.fill[0]
        if format_spec.zero:
            zero = '0'

        precision_part = ""
        if format_spec.precision:
            precision_part = ".%s" % format_spec.precision

        # -- FORMAT-SPEC: [[fill]align][0][width][.precision][type]
        return "%s%s%s%s%s%s" % (fill, align, zero, width,
                                 precision_part, format_spec.type)