title: Date range in specific format in python
body: <p>I have to put start_date and end_date in python.
  My requirement is I want date_range in the below mention format.</p>
  
  <pre><code>from datetime import datetime, timedelta
  
  a = 'yesterday' # I don't want to hardcore the date value
  b = '7daysAgo'
  start_date = a 00:00:00
  end_date = b 23:59:59
  </code></pre>
  
  <p>the hour min &amp; second in should be same, it will not be impacted whenever time I used the code.
  Please suggest</p>