old_contents: export const toJsString = function (arr) {
    return "";
  };
  
new_contents: function letToVar(arr) {
    return `var ${arr[1]} = ${arr[2]};`;
  }
  
  function addition(arr) {
    return `${arr[1]} + ${arr[2]};`;
  }
  
  export const toJsString = function (arr) {
    if (typeof arr !== 'object' || typeof arr.length !== 'number') {
      return "";
    }
  
    switch(arr[0]) {
      case 'let': return letToVar(arr);
      case '+': return addition(arr);
    }
  
    return "";
  };
  
subject: add super naive implementations for variables and additions, fails the complex test case spectacularly