'Return a condition on z under which the series converges.'

@property
def convergence_statement(self):

    from sympy import And, Or, re, Ne, oo
    R = self.radius_of_convergence
    if (R == 0):
        return False
    if (R == oo):
        return True
    e = self.eta
    z = self.argument
    c1 = And((re(e) < 0), (abs(z) <= 1))
    c2 = And((0 <= re(e)), (re(e) < 1), (abs(z) <= 1), Ne(z, 1))
    c3 = And((re(e) >= 1), (abs(z) < 1))
    return Or(c1, c2, c3)
