title: How do i convert the simple system 24 hour format to Timestamp
body: <p>I want to retrieve slack messages pasted between 4 pm to 4:30 pm daily from a certain slack channel. 
  Slack provides a Web API for a channel as <a href="https://api.slack.com/methods/channels.history" rel="noreferrer">https://api.slack.com/methods/channels.history</a> </p>
  
  <p>The above API provides 2 attributes as <code>latest</code> &amp; <code>oldest</code> , this means i can extract the messages between these 2 timestamps. But my problem is that these are time stamp and i have to make a request for timestamp as:</p>
  
  <pre><code>latest  1459750060.000002   #end
  
  oldest  1459750060.000002   #start
  </code></pre>
  
  <p>I want to pass the 2 data as simple time objects i.e </p>
  
  <pre><code>latest_simple = 0430pm     #end
  oldest_simple = 0400pm     #start
  latest_real_format = convert_to_timestamp(latest_simple)
  oldest_real_format = convert_to_timestamp(oldest_simple ) 
  </code></pre>
  
  <p>so if somehow i am able to get the timestamp , then i will easily be able to send make request to API as </p>
  
  <pre><code>payload = {'token': 'XXXXXXXx', 'channel': 'C0L8MGLMN' , 'latest': latest_real_format , 'oldest':oldest_real_format  }
  r = requests.get('https://slack.com/api/channels.history', params=payload)
  </code></pre>
  
  <p>How can i do this ?</p>