def find_DN(eq):
 (var, coeff, diop_type) = classify_diop(eq, _dict=False)
 if (diop_type == 'binary_quadratic'):
  return _find_DN(var, coeff)

def find_DN ( eq ) : ( var , coeff , diop_type ) = classify_diop ( eq , _dict = False ) if ( diop_type == 'binary_quadratic' ) : return _find_DN ( var , coeff )
this function returns a tuple .