def run(self, scale, accuracy='integrate', **kwargs):
        """Return the Wilson coefficients  (as wcxf.WC instance) evolved to the
        scale `scale`.

        Parameters:

        - `scale`: scale in GeV
        - accuracy: whether to use the numerical solution to the RGE
        ('integrate', the default, slow but precise) or the leading logarithmic
        approximation ('leadinglog', approximate but much faster).
        """
        if accuracy == 'integrate':
            C_out = self._rgevolve(scale, **kwargs)
        elif accuracy == 'leadinglog':
            C_out = self._rgevolve_leadinglog(scale)
        else:
            raise ValueError("'{}' is not a valid value of 'accuracy' (must be either 'integrate' or 'leadinglog').".format(accuracy))
        return self._to_wcxf(C_out, scale)