How to use the merkletreejs.MerkleTree function in merkletreejs

const valid_withdrawals = await withdraw_search(argv.slot, true, argv.accountId, argv.tokenId)
    console.log(valid_withdrawals)
    if (valid_withdrawals.length == 0) {
      callback(`Error: No valid withdraw found in slot ${argv.slot}`)
    }

    console.log("Reconstructing Merkle Tree from leaf nodes")
    const all_withdraws = await withdraw_search(argv.slot)
    const withdraw_hashes = Array(2 ** 7).fill(Buffer.alloc(32))
    for (let i = 0; i < all_withdraws.length; i++) {
      const withdraw = all_withdraws[i]
      if (withdraw.valid) {
        withdraw_hashes[i] = encodePacked_16_8_128(parseInt(withdraw.accountId, 16), withdraw.tokenId, parseInt(withdraw.amount))
      }
    }
    const tree = new MerkleTree(withdraw_hashes, sha256)
    const claimable_root = await instance.getClaimableWithdrawHash(argv.slot)
    // Verify merkle roots agree
    if (claimable_root != toHex(tree.getRoot())) {
      callback(`Merkle Roots disagree: ${claimable_root} != ${toHex(tree.getRoot())}`)
    }

    for (let i = 0; i < valid_withdrawals.length; i++) {
      const toClaim = valid_withdrawals[i]
      if (await instance.hasWithdrawBeenClaimed.call(argv.slot, toClaim.slotIndex)) {
        console.log("Already claimed:", toClaim)
      } else {
        console.log("Attempting to claim:", toClaim)
        const leaf = encodePacked_16_8_128(argv.accountId, argv.tokenId, parseInt(toClaim.amount))
        const proof = Buffer.concat(tree.getProof(leaf).map(x => x.data))

        // Could also check if leaf if contained in withdraw_hashes

// Our specific Merkle tree implementation requires that the number of leaves is a power of 2.
  // If the number of given leaves is less than a power of 2, we need to round up to the next
  // available power of 2. We fill the remaining space with the hash of bytes32(0).
  const correctedTreeSize = Math.pow(2, Math.ceil(Math.log2(leaves.length)))
  const parsedLeaves = []
  for (let i = 0; i < correctedTreeSize; i++) {
    if (i < leaves.length) {
      parsedLeaves.push(leaves[i])
    } else {
      parsedLeaves.push(ethers.utils.keccak256('0x' + '00'.repeat(32)))
    }
  }

  // merkletreejs prefers things to be Buffers.
  const bufLeaves = parsedLeaves.map(fromHexString)
  const tree = new MerkleTree(
    bufLeaves,
    (el: Buffer | string): Buffer => {
      return fromHexString(ethers.utils.keccak256(el))
    }
  )

  const proof = tree.getProof(bufLeaves[index], index).map((element: any) => {
    return toHexString(element.data)
  })

  return proof
}

const _generateMerkleTree = function(...args) {
  const txs = Array(2 ** 7).fill(sha256(0x0))
  for (let i = 0; i < args.length; i += 2) {
    txs[args[i]] = args[i + 1]
  }
  return new MerkleTree(txs, sha256)
}
const generateMerkleTree = memoize(_generateMerkleTree, {

const mkMerkleProof = (content /*:Buffer*/, ident /*:number*/) => {
        if (content.length <= 32) { throw new Error("Content is too short to make a tree"); }
        const arr = split(content);
        const blocknum = ident % arr.length;
        const mt = new MerkleTree(arr, Util.b2hash32);
        return mkProof(mt, arr, blocknum);
    };

if (i < header.stateRoots.length) {
        elements.push(header.stateRoots[i])
      } else {
        elements.push(ethers.utils.keccak256('0x' + '00'.repeat(32)))
      }
    }

    const hash = (el: Buffer | string): Buffer => {
      return Buffer.from(ethers.utils.keccak256(el).slice(2), 'hex')
    }

    const leaves = elements.map((element) => {
      return fromHexString(element)
    })

    const tree = new MerkleTree(leaves, hash)
    const index =
      message.parentTransactionIndex - header.batch.prevTotalElements.toNumber()
    const treeProof = tree.getProof(leaves[index], index).map((element) => {
      return element.data
    })

    return {
      stateRoot: header.stateRoots[index],
      stateRootBatchHeader: header.batch,
      stateRootProof: {
        index,
        siblings: treeProof,
      },
      stateTrieWitness: rlp.encode(proof.accountProof),
      storageTrieWitness: rlp.encode(proof.storageProof[0].proof),
    }

asMerkleTree () {
    return new MerkleTree(this.asArray(), this.sha256, {
      isBitcoinTree: true
    });
  }