title: Python exercise, guidance for slicing substrings
body: <p>Please write a program which asks the user to type in a string. The program then prints out all the substrings which begin with the first character, from the shortest to the longest. Have a look at the example below.</p>
  <pre><code>Please type in a string: test
  t
  te
  tes
  test
  </code></pre>
  <p>Obviously my code is not the way it supposed to be:</p>
  <pre><code>stg = input(&quot;Please type in a string: &quot;)
  
  print(stg[0])
  print(stg[0:5])
  print(stg[0:10])
  print(stg[10:50])
  print(stg[:])
  </code></pre>