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# from jaraco.text 3.5
class FoldedCase(str):
    """
    A case insensitive string class; behaves just like str
    except compares equal when the only variation is case.

>>> s = FoldedCase('hello world')

>>> s == 'Hello World'
    True

>>> 'Hello World' == s
    True

>>> s != 'Hello World'
    False

>>> s.index('O')
    4

>>> s.split('O')
    ['hell', ' w', 'rld']

>>> sorted(map(FoldedCase, ['GAMMA', 'alpha', 'Beta']))
    ['alpha', 'Beta', 'GAMMA']

Sequence membership is straightforward.

>>> "Hello World" in [s]
    True
    >>> s in ["Hello World"]
    True

You may test for set inclusion, but candidate and elements
    must both be folded.

>>> FoldedCase("Hello World") in {s}
    True
    >>> s in {FoldedCase("Hello World")}
    True

String inclusion works as long as the FoldedCase object
    is on the right.

>>> "hello" in FoldedCase("Hello World")
    True

But not if the FoldedCase object is on the left:

>>> FoldedCase('hello') in 'Hello World'
    False

In that case, use in_:

>>> FoldedCase('hello').in_('Hello World')
    True

>>> FoldedCase('hello') > FoldedCase('Hello')
    False
    """

def __lt__(self, other):
        return self.lower() < other.lower()

def __gt__(self, other):
        return self.lower() > other.lower()

def __eq__(self, other):
        return self.lower() == other.lower()

def __ne__(self, other):
        return self.lower() != other.lower()

def __hash__(self):
        return hash(self.lower())

def __contains__(self, other):
        return super().lower().__contains__(other.lower())

def in_(self, other):
        "Does self appear in other?"
        return self in FoldedCase(other)

# cache lower since it's likely to be called frequently.
    @method_cache
    def lower(self):
        return super().lower()

def index(self, sub):
        return self.lower().index(sub.lower())

def split(self, splitter=' ', maxsplit=0):
        pattern = re.compile(re.escape(splitter), re.I)
        return pattern.split(self, maxsplit)