docs: 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)