'Returns the Gray code a distance ``delta`` (default = 1) from the
current value in canonical order.
Examples
>>> from sympy.combinatorics.graycode import GrayCode
>>> a = GrayCode(3, start=\'110\')
>>> a.next().current
\'111\'
>>> a.next(-1).current
\'010\''

def next(self, delta=1):

    return GrayCode(self.n, rank=((self.rank + delta) % self.selections))
