How to use the @webassemblyjs/ast.signature function in @webassemblyjs/ast

lookaheadAndCheck(tokens.name) === true ||
          lookaheadAndCheck(tokens.valtype) === true ||
          token.type === "keyword" // is any keyword
        ) {
          // Instruction
          fnBody.push(parseFuncInstr());
        } else {
          throw createUnexpectedToken("Unexpected token in func body");
        }

        eatTokenOfType(tokens.closeParen);
      }

      return t.func(
        fnName,
        typeRef !== undefined ? typeRef : t.signature(fnParams, fnResult),
        fnBody
      );
    }

eatTokenOfType(tokens.closeParen);
        }

        if (lookaheadAndCheck(tokens.openParen, keywords.result)) {
          eatToken(); // (

          eatToken(); // result

          result = parseFuncResult();
          eatTokenOfType(tokens.closeParen);
        }

        eatTokenOfType(tokens.closeParen);
      }

      return t.typeInstruction(id, t.signature(params, result));
    }
    /**

eatTokenOfType(tokens.closeParen);
        }

        if (lookaheadAndCheck(tokens.openParen, keywords.result)) {
          eatToken(); // (

          eatToken(); // result

          result = parseFuncResult();
          eatTokenOfType(tokens.closeParen);
        }

        eatTokenOfType(tokens.closeParen);
      }

      return t.typeInstruction(id, t.signature(params, result));
    }
    /**

eatToken();
            fnResult.push.apply(fnResult, _toConsumableArray(parseFuncResult()));
          } else {
            throw function () {
              return new Error("\n" + codeFrameFromSource(source, token.loc) + "\n" + "Unexpected token in import of type" + ", given " + tokenToString(token));
            }();
          }

          eatTokenOfType(tokens.closeParen);
        }

        if (typeof fnName === "undefined") {
          throw new Error("Imported function must have a name");
        }

        descr = t.funcImportDescr(fnName, typeRef !== undefined ? typeRef : t.signature(fnParams, fnResult));
      } else if (isKeyword(token, keywords.global)) {
        eatToken(); // keyword

        if (token.type === tokens.openParen) {
          eatToken(); // (

          eatTokenOfType(tokens.keyword); // mut keyword

          var valtype = token.value;
          eatToken();
          descr = t.globalType(valtype, "var");
          eatTokenOfType(tokens.closeParen);
        } else {
          var _valtype = token.value;
          eatTokenOfType(tokens.valtype);
          descr = t.globalType(_valtype, "const");

let params = [];
      let result = [];

      if (token.type === tokens.identifier) {
        id = identifierFromToken(token);
        eatToken();
      }

      if (lookaheadAndCheck(tokens.openParen, keywords.func)) {
        eatToken(); // (
        eatToken(); // func

        if (token.type === tokens.closeParen) {
          eatToken();
          // function with an empty signature, we can abort here
          return t.typeInstruction(id, t.signature([], []));
        }

        if (lookaheadAndCheck(tokens.openParen, keywords.param)) {
          eatToken(); // (
          eatToken(); // param

          params = parseFuncParam();

          eatTokenOfType(tokens.closeParen);
        }

        if (lookaheadAndCheck(tokens.openParen, keywords.result)) {
          eatToken(); // (
          eatToken(); // result

          result = parseFuncResult();

code.push(callNode);
        instructionAlreadyCreated = true;
      } else if (instruction.name === "call_indirect") {
        var _startLoc10 = getPosition();

        var indexU32 = readU32();
        var typeindex = indexU32.value;
        eatBytes(indexU32.nextIndex);
        dump([typeindex], "type index");
        var signature = state.typesInModule[typeindex];

        if (typeof signature === "undefined") {
          throw new CompileError("call_indirect signature not found (".concat(typeindex, ")"));
        }

        var _callNode = t.callIndirectInstruction(t.signature(signature.params, signature.result), []);

        var flagU32 = readU32();
        var flag = flagU32.value; // 0x00 - reserved byte

        eatBytes(flagU32.nextIndex);

        if (flag !== 0) {
          throw new CompileError("zero flag expected");
        }

        code.push(function () {
          var endLoc = getPosition();
          return t.withLoc(_callNode, endLoc, _startLoc10);
        }());
        instructionAlreadyCreated = true;
      } else if (instruction.name === "br_table") {

var result = [];

      if (token.type === tokens.identifier) {
        id = identifierFromToken(token);
        eatToken();
      }

      if (lookaheadAndCheck(tokens.openParen, keywords.func)) {
        eatToken(); // (

        eatToken(); // func

        if (token.type === tokens.closeParen) {
          eatToken(); // function with an empty signature, we can abort here

          return t.typeInstruction(id, t.signature([], []));
        }

        if (lookaheadAndCheck(tokens.openParen, keywords.param)) {
          eatToken(); // (

          eatToken(); // param

          params = parseFuncParam();
          eatTokenOfType(tokens.closeParen);
        }

        if (lookaheadAndCheck(tokens.openParen, keywords.result)) {
          eatToken(); // (

          eatToken(); // result

eatTokenOfType(tokens.closeParen);
        }

        if (lookaheadAndCheck(tokens.openParen, keywords.result)) {
          eatToken(); // (
          eatToken(); // result

          result = parseFuncResult();

          eatTokenOfType(tokens.closeParen);
        }

        eatTokenOfType(tokens.closeParen);
      }

      return t.typeInstruction(id, t.signature(params, result));
    }

* (result)`
           */
          if (token.type !== tokens.closeParen) {
            results.push(...parseFuncResult());
          }
        } else {
          eatTokenOfType(tokens.openParen);

          instrs.push(parseFuncInstr());
        }

        eatTokenOfType(tokens.closeParen);
      }

      return t.callIndirectInstruction(
        typeRef !== undefined ? typeRef : t.signature(params, results),
        instrs
      );
    }

var importDescr = void 0;

      if (descrType === "func") {
        var indexU32 = readU32();
        var typeindex = indexU32.value;
        eatBytes(indexU32.nextIndex);
        dump([typeindex], "type index");
        var signature = state.typesInModule[typeindex];

        if (typeof signature === "undefined") {
          throw new CompileError("function signature not found (".concat(typeindex, ")"));
        }

        var id = getUniqueName("func");
        importDescr = t.funcImportDescr(id, t.signature(signature.params, signature.result));
        state.functionsInModule.push({
          id: t.identifier(name.value),
          signature: signature,
          isExternal: true
        });
      } else if (descrType === "global") {
        importDescr = parseGlobalType();
        var globalNode = t.global(importDescr, []);
        state.globalsInModule.push(globalNode);
      } else if (descrType === "table") {
        importDescr = parseTableType(i);
      } else if (descrType === "mem") {
        var memoryNode = parseMemoryType(0);
        state.memoriesInModule.push(memoryNode);
        importDescr = memoryNode;
      } else {