How can we modify the existing files by replacing a string `"string"` with counter incremented values as follows.

**Note1:** The first `"string"` is skipped.
**Note2**: Also the "string" will not appear for more than one time in one line.
**Note 3**: foo "string"bar -> foo "string"1bar is correct

File1 (`"string"` occurs once inside the file in any line)

```
some text
"string" here

```

File2 (`"string"` occurs thrice inside the file in any line)

```
some text
"string" here
some more
text "string"
why "string"

```

File3 (`"string"` does not occur inside the file in any line)

```
some text
why here
some more>
text pttn
why pttn

```

File4 (`"string"` occurs once inside the file in any line)

```
some "string"
no here

```

How can I replace the `"string"` with `"string"1` `"string"2`, `"string"3` etc?

**Expected Output:**

File1

```
some text
"string" here

```

File2

```
some text
"string"1 here
some more
text "string"2
why "string"3

```

File3

```
some text
why here
some more
text pttn
why pttn

```

File4

```
some "string"4
no here

```