docs: def fun_residuals(params, xnor, ynor, w, bbox, k, ext):
      """Compute fit residuals"""
  
      spl = LSQUnivariateSpline(
          x=xnor,
          y=ynor,
          t=[item.value for item in params.values()],
          w=w,
          bbox=bbox,
          k=k,
          ext=ext,
          check_finite=False
      )
      return spl.get_residual()