def ops(i, o):
 ops = set()
 (variables, orphans) = variables_and_orphans(i, o)
 for r in variables:
  if ((r not in i) and (r not in orphans)):
   if (r.owner is not None):
    ops.add(r.owner)
 return ops

def ops ( i , o ) : ops = set ( ) ( variables , orphans ) = variables_and_orphans ( i , o ) for r in variables : if ( ( r not in i ) and ( r not in orphans ) ) : if ( r . owner is not None ) : ops . add ( r . owner ) return ops
set of ops contained within the subgraph between i and o parameters i : list input variables .