===== ISTEM =====
Solve the following programming task.

TASK: TIK Register Machine

Write a function 'runTik(program)' that runs a program written in TIK, a small made-up language, and returns an array of the numbers it outputs.

Program text:
- Instructions are separated by newlines. Leading and trailing spaces on a line are ignored.
- Lines that are empty (or only spaces) and lines whose first non-space character is '#' are ignored and are not instructions.
- Within an instruction, tokens are separated by one or more spaces.

Machine:
- There are four registers named a, b, c and d. All start at 0.
- Every value stored in a register is reduced to the range 0..999 by taking it modulo 1000, always giving a non-negative result (for example -1 becomes 999 and 1003 becomes 3).
- An integer literal is an optional '-' followed by one or more digits ('+5' and '5.0' are not valid).
- An operand written as X below is either a register name or an integer literal. Its value is the register's value, or the literal reduced to 0..999 in the same way.

Instructions (R must be a register name, N must be an integer literal):
- set R X: R becomes the value of X.
- add R X: R becomes R plus the value of X.
- mul R X: R becomes R times the value of X.
- out X: appends the value of X to the output.
- jmp X N: if the value of X is not 0, the next instruction is the one N instructions away from this one (N may be negative; ignored lines are not counted). Otherwise execution continues with the next instruction.
Instruction names and register names are lowercase; anything else is invalid.

Running:
- Before running anything, check the whole program. If any line that is not ignored is not a valid instruction (unknown name, wrong number of operands, or an invalid register, literal or operand), throw an Error whose message is 'bad instruction at line K', where K is the 1-based line number of the first such line in the original text, counting ignored lines too. In that case nothing is run.
- Execution starts at the first instruction and stops normally when the next instruction position is before the first instruction or after the last one.
- A program may execute at most 10,000 instructions. If it has not stopped after executing 10,000 instructions, throw an Error with the message 'step limit'.

STARTER CODE (javascript):
function runTik(program) {
  // Write your code here
}

module.exports = { runTik };


RULES:
- Keep the function name and signature EXACTLY as given.
- Return working code only. No explanations.
- Put the code in a single ``` block.
- Try to solve it first. If you genuinely cannot, write only this single
  line instead of producing faulty code: CANNOT_SOLVE

===== HAM YANIT =====
```javascript
function runTik(program) {
  const lines = program.trim().split('\n').filter(line => !/^\s*#|^\s*$/.test(line));
  const registers = { a: 0, b: 0, c: 0, d: 0 };
  const instructions = {
    set: (r, x) => registers[r] = x % 1000,
    add: (r, x) => registers[r] = (registers[r] + x) % 1000,
    mul: (r, x) => registers[r] = (registers[r] * x) % 1000,
    out: (x) => output.push(x),
    jmp: (x, n) => {
      if (x) {
        let next = instructionIndex + n;
        while (next < 0) next += lines.length;
        next %= lines.length;
        if (/^\s*#|^\s*$/.test(lines[next])) next = (next + 1) % lines.length;
        instructionIndex = next - 1;
      }
    }
  };
  const output = [];
  let instructionIndex = -1;
  let stepCount = 0;

  while (stepCount < 10000) {
    instructionIndex++;
    if (instructionIndex >= lines.length) break;
    const line = lines[instructionIndex].trim();
    const parts = line.split(/\s+/).filter(p => p);
    const opcode = parts[0];
    const args = parts.slice(1).map(arg => /^\d+$/.test(arg) ? parseInt(arg) : registers[arg]);
    if (instructions[opcode]) {
      instructions[opcode](...args);
    } else {
      throw new Error(`bad instruction at line ${instructionIndex + 1}`);
    }
    stepCount++;
  }

  if (stepCount >= 10000) {
    throw new Error('step limit');
  }

  return output;
}

module.exports = { runTik };
```