code: def get_tan_mechanisms(self):
          
  
          retval = OrderedDict()
  
          for version in sorted(IMPLEMENTED_HKTAN_VERSIONS.keys()):
              for seg in self.bpd.find_segments('HITANS', version):
                  for parameter in seg.parameter.twostep_parameters:
                      if parameter.security_function in self.allowed_security_functions:
                          retval[parameter.security_function] = parameter
  
          return retval
docs: Get the available TAN mechanisms.
  
          Note: Only checks for HITANS versions listed in IMPLEMENTED_HKTAN_VERSIONS.
  
          :return: Dictionary of security_function: TwoStepParameters objects.