Clarify lambda func name

Author: bobleesj

diffpy/snmf/containers.py

@@ -40,13 +40,13 @@ def apply_stretch(self, m):
           stretching operation, and one vector is the second derivative of the stretching operation.
         """
         normalized_grid = np.arange(len(self.grid))
-        func = lambda stretching_factor: np.interp(  # noqa: E731
+        interpolate_intensity = lambda stretching_factor: np.interp(  # noqa: E731
             normalized_grid / stretching_factor, normalized_grid, self.iq, left=0, right=0
         )
-        derivative_func = numdifftools.Derivative(func)
+        derivative_func = numdifftools.Derivative(interpolate_intensity)
         second_derivative_func = numdifftools.Derivative(derivative_func)
 
-        stretched_component = func(self.stretching_factors[m])
+        stretched_component = interpolate_intensity(self.stretching_factors[m])
         stretched_component_gra = derivative_func(self.stretching_factors[m])
         stretched_component_hess = second_derivative_func(self.stretching_factors[m])