@classmethod
def copy(cls, other):
    """ Returns a copy of a Node instance """
    node = cls(other._start, other._end)
    node._nonterminal = other._nonterminal
    node._terminal = other._terminal
    node._token = other._token
    node._completed = other._completed
    node._highest_prio = other._highest_prio
    if other._families:
        node._families = other._families[:]
    return node
