Python nltk.grammar.u终端（'；str'；）是否总是返回true？

如何定义

nltk.grammar.is_terminal（）

使用的语法？不管我在什么对象上使用这个方法，我总是得到一个

true

作为返回。但是我想检查名为

wordlist

的列表是否包含在

grammar.cfg

下安全的上下文无关语法中定义的产品，请查看

虽然我不确定这些函数应该如何使用，但是对于任何字符串输入，

的默认值总是
True

因为，首先，所有字符串都包含
\uuuuuuuuuuuuuuuuuuuuuuuuuuu散列
属性，所以它是散列字符串的函数，请参阅

因此，一个字符串需要满足以下两个条件：（1）具有
\uuuuuuuuuuuuuuuuuuuuuuuuuuuu
属性，以及（2）不是
非终端对象。因此，
nltk.grammar.is_terminal（）
总是为所有字符串返回True

那么，只有当加载语法并读取语法中的非终结符对象时，可能只有当对象被专门创建或强制转换为非终结符时，我如何使其返回False，例如

def is_nonterminal(item):
    """
    :return: True if the item is a ``Nonterminal``.
    :rtype: bool
    """
    return isinstance(item, Nonterminal)


def is_terminal(item):
    """
    Return True if the item is a terminal, which currently is
    if it is hashable and not a ``Nonterminal``.
    :rtype: bool
    """
    return hasattr(item, '__hash__') and not isinstance(item, Nonterminal)

>>> astring = 'foo bar'
>>> astring.__hash__
<method-wrapper '__hash__' of str object at 0x7f06bb0cbcc0>
>>> astring.__hash__()
8194924035431162904

class Nonterminal(object):
    """
    A non-terminal symbol for a context free grammar.  ``Nonterminal``
    is a wrapper class for node values; it is used by ``Production``
    objects to distinguish node values from leaf values.
    The node value that is wrapped by a ``Nonterminal`` is known as its
    "symbol".  Symbols are typically strings representing phrasal
    categories (such as ``"NP"`` or ``"VP"``).  However, more complex
    symbol types are sometimes used (e.g., for lexicalized grammars).
    Since symbols are node values, they must be immutable and
    hashable.  Two ``Nonterminals`` are considered equal if their
    symbols are equal.
    :see: ``CFG``, ``Production``
    :type _symbol: any
    :ivar _symbol: The node value corresponding to this
        ``Nonterminal``.  This value must be immutable and hashable.
    """