How to change active animation action for all selected objects using python?

Question

Currently my script uses this below to change the active animation action on the active object.

for a in bpy.data.actions:
    action = obj.animation_data.action
    obj.animation_data.action = bpy.data.actions.get("Another_Action")

How would I alter this to work with all selected objects instead of just the active object? My script also creates it's own custom prop which it adds to any armatures created by it. Essentially I need to first check if the object is selected/active and then check if "my_prop" exists within said object. This will keep my script only operating on armatures it's previously created (they'll have the proper bone names etc) and allow it to operate on all selected objects. If you can only help figure out how to run on selected objects without the custom prop in mind, that helps too. Thank you

Answer 1

import bpy

your_action = bpy.data.actions["Another_Action"]

for ob in bpy.context.selected_objects:
    # Skip non-armature objects
    if ob.type != 'ARMATURE': continue

    # Skip objects without your custom prop
    #
    # NOTE: if the custom prop is on the armature,
    # not the object, use `not in ob.data` instead.
    if "Custom Prop Name" not in ob: continue

    # Create the animation data if it doesn't exist
    if not ob.animation_data:
        ob.animation_data_create()

    # Set the active action
    ob.animation_data.action = your_action