def dmp_expand(polys, u, K):
 if (not polys):
  return dmp_one(u, K)
 f = polys[0]
 for g in polys[1:]:
  f = dmp_mul(f, g, u, K)
 return f

def dmp_expand ( polys , u , K ) : if ( not polys ) : return dmp_one ( u , K ) f = polys [ 0 ] for g in polys [ 1 : ] : f = dmp_mul ( f , g , u , K ) return f
multiply together several polynomials in k[x] .