mysteriousCalculatorEnv.js

GlobalEnvironment = {
  EnvironmentRecord: { 
    // built-in identifiers
    Array: '<func>',
    Object: '<func>',
    // etc...

    // custom identifiers
    mysteriousCalculator: '<func>',
    toFixedTwoPlaces: '<func>',
  },
  outer: null,
};
 
mysteriousCalculatorEnvironment = {
  EnvironmentRecord: {
    a: 10.01,
    b: 2.01,  
    mysteriousVariable: 3,
  }
  outer: GlobalEnvironment,
};

addEnvironment = {
  EnvironmentRecord: {
    result: 15.02
  }
  outer: mysteriousCalculatorEnvironment,
};

subtractEnvironment = {
  EnvironmentRecord: {
    result: 5.00
  }
  outer: mysteriousCalculatorEnvironment,
};