code: func WBBSign(sk *FP256BN.BIG, m *FP256BN.BIG) *FP256BN.ECP {
  	// compute exp = 1/(m + sk) mod q
  	exp := Modadd(sk, m, GroupOrder)
  	exp.Invmodp(GroupOrder)
  
  	// return signature sig = g1^(1/(m + sk))
  	return GenG1.Mul(exp)
  }
docs: // WBBSign places a weak Boneh-Boyen signature on message m using secret key sk