code: def transform_q(q, query):
      
      for i, child in enumerate(q.children):
          if isinstance(child, Q):
              transform_q(child, query)
          else:
              # child is (lookup, value) tuple
              where_node = query.build_filter(child)
              q.children[i] = where_node
docs: Replaces (lookup, value) children of Q with equivalent WhereNode objects.
  
      This is a pre-prep of our Q object, ready for later rendering into SQL.
      Modifies in place, no need to return.
  
      (We could do this in render_q, but then we'd have to pass the Query object
      from ConditionalAggregate down into SQLConditionalAggregate, which Django
      avoids to do in their API so we try and follow their lead here)