count slack messages posted to a channel by user

slack-messages-by-user.py

#!/usr/bin/python
'''
Script to count messages by user posted to a channel for a given date range.

Install:
# sudo pip install slackclient

Also you will need to obtain a slack API token:
    https://api.slack.com/docs/oauth-test-tokens

Usage Example:
 
# python SLACK_SEARCH_FROM=2016-11-01 SLACK_SEARCH_TO=2016-12-01 \
         SLACK_CHANNEL_NAME=general SLACK_API_TOKEN=<token> \
         slack-messages-by-user.py
'''

import os
from datetime import datetime
from slackclient import SlackClient

slack_token = os.environ["SLACK_API_TOKEN"]
channel_name = os.environ["SLACK_CHANNEL_NAME"]
date_from = os.environ["SLACK_SEARCH_FROM"]
date_to = os.environ["SLACK_SEARCH_TO"]

oldest = (datetime.strptime(date_from, "%Y-%m-%d") - datetime(1970, 1, 1)).total_seconds()
latest = (datetime.strptime(date_to, "%Y-%m-%d") - datetime(1970, 1, 1)).total_seconds()

sc = SlackClient(slack_token)

users_list = sc.api_call("users.list")
users = {}
for user in users_list['members']:
    users[user['id']] = user['profile']['first_name'] + ' ' + user['profile']['last_name']

channels = sc.api_call("channels.list")
channel_id = None
for channel in channels['channels']:
    if channel['name'] == channel_name:
        channel_id = channel['id']
if channel_id == None:
    raise Exception("cannot find channel " + channel_name)

history = sc.api_call("channels.history", channel=channel_id, oldest=oldest, latest=latest)
posts_by_user = {}

for message in history['messages']:
    if message['user'] in posts_by_user:
        posts_by_user[users[message['user']]] += 1
    else:
        posts_by_user[users[message['user']]] = 1

for user, count in posts_by_user.items():
    print user, 'posted', count, 'messages'

Its shows error in method depreciation