def keys(min=None, max=None, excludemin=False, excludemax=False):
    """Return an :class:`~BTrees.Interfaces.IReadSequence` containing the keys in the collection.

        The type of the :class:`~BTrees.Interfaces.IReadSequence` is not specified.  It could be a list
        or a tuple or some other type.

        All arguments are optional, and may be specified as keyword
        arguments, or by position.

        If a min is specified, then output is constrained to keys greater
        than or equal to the given min, and, if excludemin is specified and
        true, is further constrained to keys strictly greater than min.  A
        min value of None is ignored. If min is None or not specified, and
        excludemin is true, the smallest key is excluded.

        If a max is specified, then output is constrained to keys less than
        or equal to the given max, and, if excludemax is specified and
        true, is further constrained to keys strictly less than max.  A max
        value of None is ignored.  If max is None or not specified, and
        excludemax is true, the largest key is excluded.
        """
