def METHOD_NAME(self, getter=None):
    """
    Returns true if this item is the start of a new group,
    where groups mean that some attribute has changed.  The getter
    can be None (the item itself changes), an attribute name like
    ``'.attr'``, a function, or a dict key or list index.
    """
    if self.first:
        return True
    return self._compare_group(self.item, self.previous, getter)