taproot – how should p2tr script trees be formatted/ordered in bitcoinjs-lib

i’m looking at the p2tr examples in the bitcoinjs-lib repo and many of them are structuring the script trees in what seemingly seems arbitrary. check out the example below taken from this file on line 248:

const scriptTree: Taptree = [
      [
        {
          output: bitcoin.script.fromASM(
            '50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0 OP_CHECKSIG',
          ),
        },
        [
          {
            output: bitcoin.script.fromASM(
              '50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac1 OP_CHECKSIG',
            ),
          },
          {
            output: bitcoin.script.fromASM(
              '2258b1c3160be0864a541854eec9164a572f094f7562628281a8073bb89173a7 OP_CHECKSIG',
            ),
          },
        ],
      ],
      [
        {
          output: bitcoin.script.fromASM(
            '50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac2 OP_CHECKSIG',
          ),
        },
        [
          {
            output: bitcoin.script.fromASM(
              '50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac3 OP_CHECKSIG',
            ),
          },
          [
            {
              output: bitcoin.script.fromASM(
                '50929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac4 OP_CHECKSIG',
              ),
            },
            {
              output: leafScript,
            },
          ],
        ],
      ],
    ];

like how do i make sense of this?