title: Write a function sum_integers(start, end) that takes two positive integers, start and end , and returns the sum of all integers
body: <p>I am a beginner at python programming, and I am doing a question like this, the question is:</p>
  <p>Write a function sum_integers(start, end) that takes two positive integers, start and end, and returns the sum of all integers comprised between start and end inclusive. The method should return <code>-1</code> if: <code>end &lt; start; start &lt; 0; end &lt; 0</code></p>
  <p>I do not know how to start a question like this, if anyone can help me i will really be appreciated.The code is below:</p>
  <pre><code>def sum_integers(x,y):
      &quot;&quot;&quot;return the sum of all integers comprised between start and end inclusive&quot;&quot;&quot;
      for value in range(x,y):
          value += 0
      return sum_integers(x,y)
  </code></pre>