code: def _get_LDAP_connection():
      
      server = ldap3.Server('ldap://' + get_optional_env('EPFL_LDAP_SERVER_FOR_SEARCH'))
      connection = ldap3.Connection(server)
      connection.open()
  
      return connection, get_optional_env('EPFL_LDAP_BASE_DN_FOR_SEARCH')
docs: Return a LDAP connection