def rewriterule(source, target, variables=(), condition=None, assume=None):
 def rewrite_rl(expr, assumptions=True):
  for match in unify(source, expr, {}, variables=variables):
   if (condition and (not condition(*[match.get(var, var) for var in variables]))):
    continue
   if (assume and (not ask(assume.xreplace(match), assumptions))):
    continue
   expr2 = subs(match)(target)
   if isinstance(expr2, Expr):
    expr2 = rebuild(expr2)
   (yield expr2)
 return rewrite_rl

def rewriterule ( source , target , variables = ( ) , condition = None , assume = None ) : def rewrite_rl ( expr , assumptions = True ) : for match in unify ( source , expr , { } , variables = variables ) : if ( condition and ( not condition ( * [ match . get ( var , var ) for var in variables ] ) ) ) : continue if ( assume and ( not ask ( assume . xreplace ( match ) , assumptions ) ) ) : continue expr2 = subs ( match ) ( target ) if isinstance ( expr2 , Expr ) : expr2 = rebuild ( expr2 ) ( yield expr2 ) return rewrite_rl
rewrite rule transform expressions that match source into expressions that match target treating all variables as wilds .