distraction2

f [ list of x-variables ] [ list of D-variables ] [ list of s-variables ]
   distraction2  result 
Example 1: [(x,y) ring_of_differential_operators 0] define_ring 
  (x^2 Dx Dy + x Dy). [(x). (y).] [(Dx). (Dy).] [(x). (y).] distraction2
Example 2: (x^4 Dx^2 + x^2). [(x).] [(Dx). ] [(x).] distraction2