def METHOD_NAME(self):
    """
    Check that ``self`` is a valid decorated permutation.
    EXAMPLES::
        sage: S = DecoratedPermutations(3)
        sage: elt = S([2, 1, -3])
        sage: elt.check()
        sage: elt = S([2, -1, 3])
        Traceback (most recent call last):
        ...
        ValueError: invalid decorated permutation
    """
    if self not in self.parent():
        raise ValueError("{} is not a decorated permutation".format(self))