'.replacements is a list of tuples (fpat, rex, s):
fpatt: a string specifying a filter pattern.
rex: a regular expression, as string.
s: the replacement string'

def configure(self, updated):

    if ('replacements' in updated):
        lst = []
        for rep in ctx.options.replacements:
            (fpatt, rex, s) = parse_hook(rep)
            flt = flowfilter.parse(fpatt)
            if (not flt):
                raise exceptions.OptionsError(('Invalid    filter    pattern:    %s' % fpatt))
            try:
                re.compile(rex)
            except re.error as e:
                raise exceptions.OptionsError(('Invalid    regular    expression:    %s    -    %s' % (rex, str(e))))
            if (s.startswith('@') and (not os.path.isfile(s[1:]))):
                raise exceptions.OptionsError('Invalid    file    path:    {}'.format(s[1:]))
            lst.append((rex, s, flt))
        self.lst = lst
