title: Is it possible to run a python file from the command line, but interact with it? (REPL)
body: <p>Suppose I have a very simple <code>test.py</code>, and here is the code:</p>
  
  <pre><code>def sum(a, b):
      return a + b
  
  
  print(sum(5, 6))
  </code></pre>
  
  <p>In my <code>cmd</code>, when I do <code>python test.py</code>, the command lines returns <code>11</code>.</p>
  
  <p>What I would like to do is <strong>interact</strong> with it, so I want to type, <code>sum(4,2)</code> and the command line should return <code>6</code>, but instead I get:</p>
  
  <p><code>sum is not recognized as an internal or external command ...</code></p>
  
  <p>Basically I want to have the <code>REPL</code> feature, like <code>WingIDE</code>, <code>Sublime Text</code>. Is this possible from the command line? </p>