docs: def verifyChainFromCAFile(self, cafile, untrusted_file=None):
          """
          Does the same job as .verifyChain() but using the list of anchors
          from the cafile. As for .verifyChain(), a list of untrusted
          certificates can be passed (as a file, this time).
          """
          try:
              f = open(cafile, "rb")
              ca_certs = f.read()
              f.close()
          except Exception:
              raise Exception("Could not read from cafile")
  
          anchors = [Cert(c) for c in split_pem(ca_certs)]
  
          untrusted = None
          if untrusted_file:
              try:
                  f = open(untrusted_file, "rb")
                  untrusted_certs = f.read()
                  f.close()
              except Exception:
                  raise Exception("Could not read from untrusted_file")
              untrusted = [Cert(c) for c in split_pem(untrusted_certs)]
  
          return self.verifyChain(anchors, untrusted)