title: Warning: SetOperator than SetProduct
body: <p>Has anyone idea what the following means:</p>
  <pre><code>[    0.00] Creating model
  WARNING: Extracting subsets for Set Distances_to_I_index_1, which is a
      SetOperator other than a SetProduct.  Returning this set and not
      descending into the set operands.  To descend into this operator, specify
      'subsets(expand_all_set_operators=True)' or to suppress this warning,
      specify 'subsets(expand_all_set_operators=False)'
  WARNING: Extracting subsets for Set Distances_to_I_index_1, which is a
      SetOperator other than a SetProduct.  Returning this set and not
      descending into the set operands.  To descend into this operator, specify
      'subsets(expand_all_set_operators=True)' or to suppress this warning,
      specify 'subsets(expand_all_set_operators=False)'
  WARNING: Extracting subsets for Set Distances_to_I_index_1, which is a
      SetOperator other than a SetProduct.  Returning this set and not
      descending into the set operands.  To descend into this operator, specify
      'subsets(expand_all_set_operators=True)' or to suppress this warning,
      specify 'subsets(expand_all_set_operators=False)'
  WARNING: Extracting subsets for Set Distances_to_I_index_1, which is a
      SetOperator other than a SetProduct.  Returning this set and not
      descending into the set operands.  To descend into this operator, specify
      'subsets(expand_all_set_operators=True)' or to suppress this warning,
      specify 'subsets(expand_all_set_operators=False)'
  [    0.03] Applying solver
  </code></pre>
  <p>I have as a result the optimal solution but should i correct sth so the warning will dismiss?</p>