How to use the ethereumjs-util.fromSigned function in ethereumjs-util

function concatSig(v, r, s) {
  r = ethUtil.fromSigned(r)
  s = ethUtil.fromSigned(s)
  v = ethUtil.bufferToInt(v)
  r = ethUtil.toUnsigned(r).toString('hex')
  s = ethUtil.toUnsigned(s).toString('hex')
  v = ethUtil.stripHexPrefix(ethUtil.intToHex(v))
  return ethUtil.addHexPrefix(r.concat(s, v).toString("hex"))
}

concatSig: function (v, r, s) {
    const rSig = ethUtil.fromSigned(r)
    const sSig = ethUtil.fromSigned(s)
    const vSig = ethUtil.bufferToInt(v)
    const rStr = padWithZeroes(ethUtil.toUnsigned(rSig).toString('hex'), 64)
    const sStr = padWithZeroes(ethUtil.toUnsigned(sSig).toString('hex'), 64)
    const vStr = ethUtil.stripHexPrefix(ethUtil.intToHex(vSig))
    return ethUtil.addHexPrefix(rStr.concat(sStr, vStr)).toString('hex')
  },

function concatSig (v, r, s) {
  const rSig = ethUtil.fromSigned(r)
  const sSig = ethUtil.fromSigned(s)
  const vSig = ethUtil.bufferToInt(v)
  const rStr = padWithZeroes(ethUtil.toUnsigned(rSig).toString('hex'), 64)
  const sStr = padWithZeroes(ethUtil.toUnsigned(sSig).toString('hex'), 64)
  const vStr = ethUtil.stripHexPrefix(ethUtil.intToHex(vSig))
  return ethUtil.addHexPrefix(rStr.concat(sStr, vStr)).toString('hex')
}

var concatSig = function (signature) {
  var v = signature.v;
  var r = signature.r;
  var s = signature.s;
  r = util.fromSigned(r);
  s = util.fromSigned(s);
  v = util.bufferToInt(v);
  r = util.setLengthLeft(util.toUnsigned(r), 32).toString('hex');
  s = util.setLengthLeft(util.toUnsigned(s), 32).toString('hex');
  v = util.stripHexPrefix(util.intToHex(v));
  return util.addHexPrefix(r.concat(s, v).toString("hex"));
};

SGT: function (a, b, runState) {
    return Buffer.from([
      utils.fromSigned(a).gt(utils.fromSigned(b))
    ])
  },
  EQ: function (a, b, runState) {

concatSig: function (v, r, s) {
    const rSig = ethUtil.fromSigned(r)
    const sSig = ethUtil.fromSigned(s)
    const vSig = ethUtil.bufferToInt(v)
    const rStr = padWithZeroes(ethUtil.toUnsigned(rSig).toString('hex'), 64)
    const sStr = padWithZeroes(ethUtil.toUnsigned(sSig).toString('hex'), 64)
    const vStr = ethUtil.stripHexPrefix(ethUtil.intToHex(vSig))
    return ethUtil.addHexPrefix(rStr.concat(sStr, vStr)).toString('hex')
  },

function concatSig (v, r, s) {
  const rSig = ethUtil.fromSigned(r)
  const sSig = ethUtil.fromSigned(s)
  const vSig = ethUtil.bufferToInt(v)
  const rStr = padWithZeroes(ethUtil.toUnsigned(rSig).toString('hex'), 64)
  const sStr = padWithZeroes(ethUtil.toUnsigned(sSig).toString('hex'), 64)
  const vStr = ethUtil.stripHexPrefix(ethUtil.intToHex(vSig))
  return ethUtil.addHexPrefix(rStr.concat(sStr, vStr)).toString('hex')
}

export const concatSig = (v, r, s) => {
  const rSig = ethUtil.fromSigned(r);
  const sSig = ethUtil.fromSigned(s);
  const vSig = ethUtil.bufferToInt(v);
  const rStr = padWithZeroes(ethUtil.toUnsigned(rSig).toString('hex'), 64);
  const sStr = padWithZeroes(ethUtil.toUnsigned(sSig).toString('hex'), 64);
  const vStr = ethUtil.stripHexPrefix(ethUtil.intToHex(vSig));
  return ethUtil.addHexPrefix(rStr.concat(sStr, vStr)).toString('hex');
};