code: def makeCredentials(path, email):
      
      key = _generateKey()
      cert = _makeCertificate(key, email)
  
      certPath = path.child("client.pem")
      certPath.alwaysCreate = True
  
      with certPath.open("wb") as pemFile:
          pemFile.write(dump_privatekey(FILETYPE_PEM, key))
          pemFile.write(dump_certificate(FILETYPE_PEM, cert))
docs: Make credentials for the client from given e-mail address and store
      them in the directory at path.