How to select all objects with same normals direction in 3Ds Max using maxscript or pymxs?

Need help to write the code on Python (pymxs) or Maxscript which can allow to select all objects with same normals direction in 3Ds Msx.

I have this base function, but can't achieve needed result.

import pymxs
def select_same_normal_objects(normal_dir):
    selection_set = []
    geometry_objects = list(rt.execute('''for o in geometry where (isKindOf o GeometryClass and canConvertTo o Editable_Mesh) collect o'''))
    for obj in geometry_objects:
        if obj.getNormal() == normal_dir:
            selection_set.append(obj)
    return selection_set

Based on the comments above, specifically this statement

I have to select all faces of objects whose normals look in one direction

you could do something like:

def select_same_normal_objects(normal_dir):
    selection_dict = dict()
    geometry_objects = list(rt.execute("for o in geometry where (isKindOf o GeometryClass and canConvertTo o Editable_Mesh) collect o"))
    
    for obj in geometry_objects:
        
        # get a "get face normal" function for the obj type
        getFaceNormal = None
        if str(rt.classof(obj)) == 'Editable_Poly':
            getFaceNormal = pymxs.runtime.polyop.getFaceNormal
        elif str(rt.classof(obj)) == 'Editable_mesh':
            getFaceNormal = pymxs.runtime.getFaceNormal
        else:
            pass  # implement getFaceNormal() for other object types

        if getFaceNormal:
            for i in range(pymxs.runtime.getNumFaces(obj)):
                # careful that maxscript has one-based indices
                normal = getFaceNormal(obj, i+1)
                if normal == normal_dir:
                    if obj not in selection_dict:
                        selection_dict[obj] = [i+1]
                    else:
                        selection_dict[obj].append(i+1)
    return selection_dict

This returns you a dictionary with all found faces per object

{
   obj1: [1,2,4,...],
   obj2: [5,11,...],
   ...
}