title: Comparing a list of integers with a number prolog
body: <p>I have to define a predicate which takes as input a list of integers, and instantiates X with the elements of L smaller than 10, and Y with the elements of the list greater than or equal to 10.</p>
  <p>This is the predicate: <code>separate(L, X, Y)</code></p>
  <p>Here are some examples of the output I'm looking for:</p>
  <pre><code>?− separate([2, 13, 4, 0, 55], X, Y).
      X = [2, 4, 0]
      Y = [13, 55]
  
  ?− separate([2, 3], X, Y).
      X = [2, 3]
      Y = [ ]
  </code></pre>