code: function checkCondition(i) {
    const start = i;
    let l;
  
    if (i >= tokensLength) return 0;
  
    if ((l = checkIdent(i)) && tokens[i].value === 'when') i += l;
    else return 0;
  
    while (i < tokensLength) {
      if (l = checkBlock(i)) {
        tokens[i].condition_child = 0;
        break;
      } else if (l = checkFunction(i)) tokens[i].condition_child = 1;
      else if (l = checkBrackets(i)) tokens[i].condition_child = 2;
      else if (l = checkParentheses(i)) tokens[i].condition_child = 3;
      else if (l = checkVariable(i)) tokens[i].condition_child = 4;
      else if (l = checkIdent(i)) tokens[i].condition_child = 5;
      else if (l = checkNumber(i)) tokens[i].condition_child = 6;
      else if (l = checkDelim(i)) tokens[i].condition_child = 7;
      else if (l = checkOperator(i)) tokens[i].condition_child = 8;
      else if (l = checkCombinator(i)) tokens[i].condition_child = 9;
      else if (l = checkSC(i)) tokens[i].condition_child = 10;
      else if (l = checkString(i)) tokens[i].condition_child = 11;
      else return 0;
  
      i += l;
    }
  
    return i - start;
  }
docs: Check if token is part of a condition.
  @param {Number} i Token's index number
  @return {Number} Length of the condition