code: func (BitCurve *BitCurve) Marshal(x, y *big.Int) []byte {
  	byteLen := (BitCurve.BitSize + 7) >> 3
  	ret := make([]byte, 1+2*byteLen)
  	ret[0] = 4 // uncompressed point flag
  	readBits(x, ret[1:1+byteLen])
  	readBits(y, ret[1+byteLen:])
  	return ret
  }
docs: // Marshal converts a point into the form specified in section 4.3.6 of ANSI
  // X9.62.