title: Getting TSLint interface error while pushing value into multidimensional array
body: <p>I am converting response into Month and Day array and in Day array I have number array. The logic is working fine as expected, But I am getting tslint error near pushing the value into day array,</p>
  <p><strong>Error - Argument of type 'number' is not assignable to parameter of type 'DayTimeData'.</strong></p>
  <p>Here is the my interface code -</p>
  <pre><code>export interface SerializeHourValData {
    name: string;
    data: MonthDateTimeData[];
  }
  
  export interface MonthDateTimeData {
    [month: number]: DayTimeData[];
  }
  
  export interface DayTimeData {
    [day: number]: number[];
  }
  </code></pre>
  <p>And logical code where I am getting error</p>
  <pre><code>public valData: SerializeHourValData[] = [];
  
  // Here I am looping through and getting month &amp; day number and from using that I am storing hourlyData in day.
  
  this.valData[index].data[month] = this.valData[index].data[month] || [];
      this.valData[index].data[month][day] = this.valData[index].data[month][day] || [];
  
      for (const key in hourlyData) {
        if (key.indexOf('h') &gt; -1) {
          this.valData[index].data[month][day].push(+hourlyData[key]); // here i am getting Tslint error for '+hourlyData[key]'
        }
      } 
  </code></pre>
  <p><a href="https://i.stack.imgur.com/mRbwY.png" rel="nofollow noreferrer">Here is the snapshot how data looks after serialization -</a></p>
  <p>Let me know where i was wrong in interface.</p>