I started learning typescript, so I'm creating situations to resolve, I'm getting error not sure why, see code above: 

```
interface IObjct {
  name: string,
  city: string,
  age: number,
}

const john = {
  name: "John",
  city: "London",
  age: 24
};

const jerry = {
 name: "Jerry",
 city: "Rome",
 age: 43
};

function filterPerson(arr: Array<IObjct>, term: string, key: string) {
  return arr.filter(function(person) {
    return person[key].match(term);
  });
}

```

I'm getting error on line : return person[key].match(term);

person[key]

Element implicitly has an 'any' type because expression of type 'string' can't be used to index type 'IObjct'.

No index signature with a parameter of type 'string' was found on type 'IObjct'.ts(7053)

```
filterPerson([john, jerry], "London", "city");

```