code: def set_mac_address(self, mac_address=None, default=False, disable=False):
          
          base_command = 'ip virtual-router mac-address'
          if not default and not disable:
              if mac_address is not None:
                  # Check to see if mac_address matches expected format
                  if not re.match(r'(?:[a-f0-9]{2}:){5}[a-f0-9]{2}',
                                  mac_address):
                      raise ValueError('mac_address must be formatted like:'
                                       'aa:bb:cc:dd:ee:ff')
              else:
                  raise ValueError('mac_address must be a properly formatted '
                                   'address string')
          if default or disable and not mac_address:
              current_mac = self._parse_mac_address()
              if current_mac['mac_address']:
                  base_command = base_command + ' ' + current_mac['mac_address']
          commands = self.command_builder(base_command, value=mac_address,
                                          default=default, disable=disable)
          return self.configure(commands)
docs: Sets the virtual-router mac address
  
          This method will set the switch virtual-router mac address. If a
          virtual-router mac address already exists it will be overwritten.
  
          Args:
              mac_address (string): The mac address that will be assigned as
                  the virtual-router mac address. This should be in the format,
                  aa:bb:cc:dd:ee:ff.
              default (bool): Sets the virtual-router mac address to the system
                  default (which is to remove the configuration line).
              disable (bool): Negates the virtual-router mac address using
                  the system no configuration command
  
          Returns:
              True if the set operation succeeds otherwise False.