[
  {
    fn: {
      name: "fact",
      args: ["n"],
      body: [
        { let: { result: { var: "fact.n" } } },
        {
          loop: [
            //using loop because recursion is not supported
            {
              if: {
                condition: { comp: [{ var: "fact.n" }, ">", 1] },
                body: [
                  {
                    assign: {
                      "fact.n": {
                        calc: [{ var: "fact.n" }, "-", 1],
                      },
                    },
                  },
                  {
                    assign: {
                      result: {
                        calc: [{ var: "result" }, "*", { var: "fact.n" }],
                      },
                    },
                  },
                ],
                else: ["break"],
              },
            },
          ],
        },
        { return: { var: "result" } },
      ],
    },
  },

  {
    fn: {
      name: "_eq",
      args: ["a", "b"],
      body: [{ return: { comp: [{ var: "_eq.a" }, "==", { var: "_eq.b" }] } }],
    },
  },

  ["10! == 3 628 800: ", { _eq: [{ fact: [10] }, 3628800] }],
  ["11! == 39 916 800: ", { _eq: [{ fact: [11] }, 39916800] }],

  ["12! == 479 001 600: ", { _eq: [{ fact: [12] }, 479001600] }],
  ["13! == 6 227 020 800: ", { _eq: [{ fact: [13] }, 6227020800] }],

  ["14! == 87 178 291 200: ", { _eq: [{ fact: [14] }, 87178291200] }],
  ["15! == 1 307 674 368 000: ", { _eq: [{ fact: [15] }, 1307674368000] }],

  ["16! == 20 922 789 888 000: ", { _eq: [{ fact: [16] }, 20922789888000] }],
  ["17! == 355 687 428 096 000: ", { _eq: [{ fact: [17] }, 355687428096000] }],

  [
    "18! == 6 402 373 705 728 000: ",
    { _eq: [{ fact: [18] }, 6402373705728000] },
  ],
  [
    "19! == 121 645 100 408 832 000: ",
    { _eq: [{ fact: [19] }, 121645100408832000] },
  ],

  [
    "20! == 2 432 902 008 176 640 000: ",
    { _eq: [{ fact: [20] }, 2432902008176640000] },
  ],
  // [
  //   "21! == 51 090 942 171 709 440 000: ",
  //   { _eq: [{ fact: [21] }, 51090942171709440000] },
  // ], some json and yaml troubles with number `51090942171709440000`
  { calc: ["operand", "+", "operand"] }
]