'Performs the action of a creation operator.
Examples
>>> from sympy.physics.secondquant import BBra
>>> b = BBra([1, 2])
>>> b
FockStateBosonBra((1, 2))
>>> b.up(1)
FockStateBosonBra((1, 3))'

def up(self, i):

    i = int(i)
    new_occs = list(self.args[0])
    new_occs[i] = (new_occs[i] + S.One)
    return self.__class__(new_occs)
