code: function getLoop() {
    const type = NodeType.LoopType;
    const token = tokens[pos];
    const line = token.ln;
    const column = token.col;
    let content = [];
  
    content.push(getAtkeyword());
  
    while (pos < tokensLength) {
      if (checkBlock(pos)) {
        content.push(getBlock());
        break;
      }
      else if (checkVariable(pos)) content.push(getVariable());
      else if (checkNumber(pos)) content.push(getNumber());
      else if (checkInterpolation(pos)) content.push(getInterpolation());
      else if (checkIdent(pos)) content.push(getIdent());
      else if (checkOperator(pos)) content.push(getOperator());
      else if (checkCombinator(pos)) content.push(getCombinator());
      else if (checkSC(pos)) content = content.concat(getSC());
      else if (checkString(pos)) content.push(getString());
    }
  
    return newNode(type, content, line, column);
  }
docs: Get node with a loop.
  @return {Array} `['loop', x]`