if not hasattr('', 'format'):
    from string import Template
    import re
    def str_format(string, *args, **kwargs):
        tpl = Template(string)
        tpl.pattern = str_format.re
        return tpl.substitute(*args, **kwargs)
    str_format.re = re.compile(r'\{(?P<named>[A-Za-z0-9_]+)\}')
else:
    def str_format(string, *args, **kwargs):
        return string.format(*args, **kwargs)