code: def verifychain_from_cafile(self, cafile, untrusted_file=None):
          
          cmd = ["openssl", "verify", "-CAfile", cafile]
          if untrusted_file:
             cmd += ["-untrusted", untrusted_file]
          try:
              pemcert = self.output(fmt="PEM")
              cmdres = self._apply_ossl_cmd(cmd, pemcert)
          except:
              return False
          return cmdres.endswith("\nOK\n") or cmdres.endswith(": OK\n")
docs: Does the same job as .verifychain() but using the list of anchors
          from the cafile. This is useful (because more efficient) if
          you have a lot of certificates to verify do it that way: it
          avoids the creation of a cafile from anchors at each call.
  
          As for .verifychain(), a list of untrusted certificates can be
          passed (as a file, this time)