'Compute formal power power series of self.
See the docstring of the :func:`fps` function in sympy.series.formal for
more information.'

def fps(self, x=None, x0=0, dir=1, hyper=True, order=4, rational=True, full=False):

    from sympy.series.formal import fps
    return fps(self, x, x0, dir, hyper, order, rational, full)
