AWS AMI deletion Python code

# Automated AMI and Snapshot Deletion
#
# @author Robert Kozora <bobby@kozora.me> [I made some changes]
#
# This script will search for all instances having a tag with "Backup" or "backup"
# on it. As soon as we have the instances list, we loop through each instance
# and reference the AMIs of that instances which has backup tag as "filter_date_fmt" variable value.
# We check that the latest daily backup
# succeeded then we store every image that's reached its DeleteOn tag's date for
# deletion. We then loop through the AMIs, deregister them and remove all the
# snapshots associated with that AMI.

import boto3
import collections
import datetime
import time
import sys

ec = boto3.client('ec2', 'ap-south-1')
ec2 = boto3.resource('ec2', 'ap-south-1')


date = datetime.datetime.now()
filter_date_fmt = date.strftime('%m-%d-%Y')

images = ec2.images.filter(Owners=["self"],Filters=[{'Name':'tag:DeleteOn','Values':["filter_date_fmt"]}])
print images

def lambda_handler(event, context):

    reservations = ec.describe_instances(

    ).get(
        'Reservations', []
    )

    instances = sum(
        [
            [i for i in r['Instances']]
            for r in reservations
        ], [])

    print "Found %d instances that need evaluated" % len(instances)

    to_tag = collections.defaultdict(list)

    #date = datetime.datetime.now()
    date_fmt = date.strftime('%Y-%m-%d')

    imagesList = []

    # Set to true once we confirm we have a backup taken today
    backupSuccess = False

    # Loop through all of our instances with a tag named "Backup"
    imagecount = 0
    for instance in instances:
        # Loop through each image of our current instance
        for image in images:

            # Our other Lambda Function names its AMIs Lambda - i-instancenumber.
            # We now know these images are auto created
            if image.name.startswith('Lambda - ' + instance['InstanceId']):

                # print "FOUND IMAGE " + image.id + " FOR INSTANCE " + instance['InstanceId']

                # Count this image's occcurance
            imagecount = imagecount + 1

                try:
                    if image.tags is not None:
                        deletion_date = [
                            t.get('Value') for t in image.tags
                            if t['Key'] == 'DeleteOn'][0]
                        delete_date = time.strptime(deletion_date, "%m-%d-%Y")
                except IndexError:
                    deletion_date = False
                    delete_date = False

                today_time = datetime.datetime.now().strftime('%m-%d-%Y')
                # today_fmt = today_time.strftime('%m-%d-%Y')
                today_date = time.strptime(today_time, '%m-%d-%Y')

                # If image's DeleteOn date is less than or equal to today,
                # add this image to our list of images to process later

                if delete_date <= today_date:
                    imagesList.append(image.id)

                # Make sure we have an AMI from today and mark backupSuccess as true
                #print date_fmt
                #print image.name
                if date_fmt in image.name:#if image.name.endswith(date_fmt):
                    # Our latest backup from our other Lambda Function succeeded
                    backupSuccess = True
                    print "Latest backup from " + date_fmt + " was a success"
                else:
                    print "Today's Backup not done yet"
        if(imagecount >= 75):
            break
        print "instance " + instance['InstanceId'] + " has " + str(imagecount) + " AMIs"

    print "============="

    print "About to process the following AMIs:"
    print imagesList

    if backupSuccess == False:

        myAccount = boto3.client('sts').get_caller_identity()['Account']
        snapshots = ec.describe_snapshots(MaxResults=1000, OwnerIds=[myAccount])['Snapshots']

        # loop through list of image IDs
        imgcount=0
        for image in imagesList:
            imgcount=imgcount+1
            print "deregistering image %s" % image
            amiResponse = ec.deregister_image(
                DryRun=False,
                ImageId=image,
            )
            print amiResponse

            for snapshot in snapshots:
                if snapshot['Description'].find(image) > 0:
                    snap = ec.delete_snapshot(SnapshotId=snapshot['SnapshotId'])
                    print "Deleting snapshot " + snapshot['SnapshotId']
                    print "-------------"
                    print snap
            if(imgcount>=75):
                break

    else:
        print "No current backup found. Termination suspended."

is it possible to add Unitest for this code as well ?