def expand(self, str, stripdot=True): # macros='slodipvh'
        """Do SPF RFC macro expansion.

        Examples:
        >>> q = query(s='strong-bad@email.example.com',
        ...           h='mx.example.org', i='192.0.2.3')
        >>> q.p = 'mx.example.org'
        >>> q.r = 'example.net'

        >>> q.expand('%{d}')
        'email.example.com'

        >>> q.expand('%{d4}')
        'email.example.com'

        >>> q.expand('%{d3}')
        'email.example.com'

        >>> q.expand('%{d2}')
        'example.com'

        >>> q.expand('%{d1}')
        'com'

        >>> q.expand('%{p}')
        'mx.example.org'

        >>> q.expand('%{p2}')
        'example.org'

        >>> q.expand('%{dr}')
        'com.example.email'
    
        >>> q.expand('%{d2r}')
        'example.email'

        >>> q.expand('%{l}')
        'strong-bad'

        >>> q.expand('%{l-}')
        'strong.bad'

        >>> q.expand('%{lr}')
        'strong-bad'

        >>> q.expand('%{lr-}')
        'bad.strong'

        >>> q.expand('%{l1r-}')
        'strong'

        >>> q.expand('%{c}',stripdot=False)
        '192.0.2.3'

        >>> q.expand('%{r}',stripdot=False)
        'example.net'

        >>> q.expand('%{ir}.%{v}._spf.%{d2}')
        '3.2.0.192.in-addr._spf.example.com'

        >>> q.expand('%{lr-}.lp._spf.%{d2}')
        'bad.strong.lp._spf.example.com'

        >>> q.expand('%{lr-}.lp.%{ir}.%{v}._spf.%{d2}')
        'bad.strong.lp.3.2.0.192.in-addr._spf.example.com'

        >>> q.expand('%{ir}.%{v}.%{l1r-}.lp._spf.%{d2}')
        '3.2.0.192.in-addr.strong.lp._spf.example.com'

        >>> try: q.expand('%(ir).%{v}.%{l1r-}.lp._spf.%{d2}')
        ... except PermError as x: print(x)
        invalid-macro-char : %(ir)

        >>> q.expand('%{p2}.trusted-domains.example.net')
        'example.org.trusted-domains.example.net'

        >>> q.expand('%{p2}.trusted-domains.example.net.')
        'example.org.trusted-domains.example.net'

        >>> q = query(s='@email.example.com',
        ...           h='mx.example.org', i='192.0.2.3')
        >>> q.p = 'mx.example.org'
        >>> q.expand('%{l}')
        'postmaster'

        """
        macro_delimiters = ['{', '%', '-', '_']
        end = 0
        result = ''
        macro_count = str.count('%')
        if macro_count != 0:
            labels = str.split('.')
            for label in labels:
                is_macro = False
                if len(label) > 1:
                    if label[0] == '%':
                        for delimit in macro_delimiters:
                            if label[1] == delimit:
                                is_macro = True
                        if not is_macro:
                            raise PermError ('invalid-macro-char ', label)
                            break
        for i in RE_CHAR.finditer(str):
            result += str[end:i.start()]
            macro = str[i.start():i.end()]
            if macro == '%%':
                result += '%'
            elif macro == '%_':
                result += ' '
            elif macro == '%-':
                result += '%20'
            else:
                letter = macro[2].lower()
#                print letter
                if letter == 'p':
                    self.getp()
                elif letter in 'crt' and stripdot:
                    raise PermError(
                        'c,r,t macros allowed in exp= text only', macro)
                expansion = getattr(self, letter, self)
                if expansion:
                    if expansion == self:
                        raise PermError('Unknown Macro Encountered', macro) 
                    e = expand_one(expansion, macro[3:-1], JOINERS.get(letter))
                    if letter != macro[2]:
                        e = urllibparse.quote(e)
                    result += e

            end = i.end()
        result += str[end:]
        if stripdot and result.endswith('.'):
            result =  result[:-1]
        if result.count('.') != 0:
            if len(result) > 253:
                result = result[(result.index('.')+1):]
        return result
Do SPF RFC macro expansion.

        Examples:
        >>> q = query(s='strong-bad@email.example.com',
        ...           h='mx.example.org', i='192.0.2.3')
        >>> q.p = 'mx.example.org'
        >>> q.r = 'example.net'

        >>> q.expand('%{d}')
        'email.example.com'

        >>> q.expand('%{d4}')
        'email.example.com'

        >>> q.expand('%{d3}')
        'email.example.com'

        >>> q.expand('%{d2}')
        'example.com'

        >>> q.expand('%{d1}')
        'com'

        >>> q.expand('%{p}')
        'mx.example.org'

        >>> q.expand('%{p2}')
        'example.org'

        >>> q.expand('%{dr}')
        'com.example.email'
    
        >>> q.expand('%{d2r}')
        'example.email'

        >>> q.expand('%{l}')
        'strong-bad'

        >>> q.expand('%{l-}')
        'strong.bad'

        >>> q.expand('%{lr}')
        'strong-bad'

        >>> q.expand('%{lr-}')
        'bad.strong'

        >>> q.expand('%{l1r-}')
        'strong'

        >>> q.expand('%{c}',stripdot=False)
        '192.0.2.3'

        >>> q.expand('%{r}',stripdot=False)
        'example.net'

        >>> q.expand('%{ir}.%{v}._spf.%{d2}')
        '3.2.0.192.in-addr._spf.example.com'

        >>> q.expand('%{lr-}.lp._spf.%{d2}')
        'bad.strong.lp._spf.example.com'

        >>> q.expand('%{lr-}.lp.%{ir}.%{v}._spf.%{d2}')
        'bad.strong.lp.3.2.0.192.in-addr._spf.example.com'

        >>> q.expand('%{ir}.%{v}.%{l1r-}.lp._spf.%{d2}')
        '3.2.0.192.in-addr.strong.lp._spf.example.com'

        >>> try: q.expand('%(ir).%{v}.%{l1r-}.lp._spf.%{d2}')
        ... except PermError as x: print(x)
        invalid-macro-char : %(ir)

        >>> q.expand('%{p2}.trusted-domains.example.net')
        'example.org.trusted-domains.example.net'

        >>> q.expand('%{p2}.trusted-domains.example.net.')
        'example.org.trusted-domains.example.net'

        >>> q = query(s='@email.example.com',
        ...           h='mx.example.org', i='192.0.2.3')
        >>> q.p = 'mx.example.org'
        >>> q.expand('%{l}')
        'postmaster'

        
python/spf.py