How to copy data from array to empty array within a document in mongodb using python?

In MongoDB collection, I want to copy current array data to previous array. Is it possible to do so

my_moongo_db_collection_object = {
                        "lifespeakerid": code, "karyaspeakerid": code,
                        "karya_info":{"username": "", "projectname": ""}, 
                        "current": {"speakerMetadata": {"name": "Om", "agegroup": "12-32", "gender": "M", 
                                                "educationlevel": "12", "educationmediumupto12": "hindi", 
                                                "educationmediumafter12": "english", "speakerspeaklanguage" :"english", 
                                                "recordingplace": "goa", "typeofrecordingplace" : "ree", 
                                                "activeAccessCode": "rd"}, "current_date":current_dt},
                        "previous": {"speakerMetadata": {"name": "", "agegroup": "", "gender": "", 
                                                "educationlevel": "", "educationmediumupto12": "", 
                                                "educationmediumafter12": "", "speakerspeaklanguage" :"", 
                                                "recordingplace": "", "typeofrecordingplace" : "", 
                                                "activeAccessCode": ""}, "previous_date":current_dt},
                        "isActive": 0}

Copying current array to previous array. Please help thanks

my_moongo_db_collection_object = {
                        "lifespeakerid": code, "karyaspeakerid": code,
                        "karya_info":{"username": "", "projectname": ""}, 
                        "current": {"speakerMetadata": {"name": "Om", "agegroup": "12-32", "gender": "M", 
                                                "educationlevel": "12", "educationmediumupto12": "hindi", 
                                                "educationmediumafter12": "english", "speakerspeaklanguage" :"english", 
                                                "recordingplace": "goa", "typeofrecordingplace" : "ree", 
                                                "activeAccessCode": "rd"}, "current_date":current_dt},
                        "previous": {"speakerMetadata": {"name": "om", "agegroup": "12-32", "gender": "M", 
                                                "educationlevel": "12", "educationmediumupto12": "hindi", 
                                                "educationmediumafter12": "english", "speakerspeaklanguage" :"english", 
                                                "recordingplace": "goa", "typeofrecordingplace" : "ree", 
                                                "activeAccessCode": "rd"}, "previous_date":current_dt},
                        "isActive": 0}