def step_psum(self,s):

        if self.variant!="v":
            if self.n==0:
                self.last_s=s
                self.run(s,s)
            else:
                self.run(s,s-self.last_s)
                self.last_s=s
        else:
            if isinstance(self.last_s,bool):
                self.last_s=s
                self.last_w=s
                self.last=0
                return s,abs(s)

            na1=s-self.last_s
            self.run(self.last_s,self.last_w,na1)
            self.last_w=na1
            self.last_s=s

        value=self.A[0]/self.B[0]
        err=abs(value-self.last)
        self.last=value

        return value,err
Testing variable-argument function signature.
dataset/ETHPy150Open fredrik-johansson/mpmath/mpmath/calculus/extrapolation.py/levin_class.step_psum--crossover with--dataset/ETHPy150Open twisted/twisted/twisted/test/test_explorer.py/BrowseFunctionTests.test_signature_variable