'Given a xpath_fmt which takes five params:
- Original value
- String delimiter
- XML filter
- XML filter result length to compare agains (@str_len)
- True condition
Generate the XPATH, send it to the remote server and
:return: True when the response does NOT contain an XPATH error.'

def _fill_xpath_and_eval(self, xpath_fmt, str_len):

    mutant = self.get_mutant()
    orig_value = mutant.get_token_original_value()
    skip_len = ((len(orig_value) + len(self.STR_DELIM)) + len('    '))
    findlen = (xpath_fmt % (orig_value, self.STR_DELIM, XML_FILTER, str_len, self.TRUE_COND[skip_len:]))
    mutant.set_token_value(findlen)
    lresp = self._uri_opener.send_mutant(mutant)
    if (not self.is_error_resp(lresp.get_body())):
        return True
    return False
