def split_on_arrow(eq):
 for arrow in ARROWS:
  (left, a, right) = eq.partition(arrow)
  if (a != ''):
   return (left, a, right)
 return (eq, '', '')

def split_on_arrow ( eq ) : for arrow in ARROWS : ( left , a , right ) = eq . partition ( arrow ) if ( a != '' ) : return ( left , a , right ) return ( eq , '' , '' )
split a string on an arrow .