title: Need to create a cluster(L , A , B) , that returns sub-lists of L on A and B respectively , based on a condition
body: <p>Let's say we have the list L = [ 1,  5 , 32 , 5 , 7, 8] 
  I need to create a cluster( L , A ,B ) which divides L in 2 sub-lists ( A , B).
  A is supposed to contain all the values that appear on list L BEFORE the value 32 . 
  B is supposed to contain all the values that appear on list L AFTER the value 32.
  32 is supposed to be excluded from both lists.</p>
  
  <pre><code>?- cluster([11 , 18 , 9 , 32 , 13 , 12 ] , A , B).
  A = [11 , 18 , 9], B = [13 ,12].
  </code></pre>