Returns the given variable's definition.

    Args:
      var: A variable the bootloader tracks, such as version.
      info_cb: See Download. Usually no messages.
    Returns:
      Value of var according to the current bootloader.

def get_var(self, var, info_cb=DEFAULT_MESSAGE_CALLBACK):
    """Returns the given variable's definition.

    Args:
      var: A variable the bootloader tracks, such as version.
      info_cb: See Download. Usually no messages.
    Returns:
      Value of var according to the current bootloader.
    """
    return self._simple_command('getvar', arg=var, info_cb=info_cb)