Boto3 help

from __future__ import division
import boto3
import os
import datetime

def lambda_handler(event, context):

date = str(datetime.date.today())
Ofile = open('/tmp/zinst.out', "w")
Sns = boto3.client('sns')
ssm = boto3.client('ssm')
Subj = os.environ['Subj']
ETopicArn = os.environ['ETopicArn']
RegionList = boto3.session.Session().get_available_regions('ec2')
for Region in RegionList:
ec = boto3.client('ec2', Region)
Conn = boto3.client('ec2', region_name=Region)

AllReserves = Conn.describe_instances()
for Reserves in AllReserves['Reservations']:
for Inst in Reserves['Instances']:
tags=(Inst['Tags'])