This week we’re going to work with file.

You’re given a file named `nums.dat`

and need to calculate the sum of all integer values in the file.

# Sum Numbers in File

For this problem you are given a file named `nums.dat`

that contains integers across multiple lines. There are multiple lines, and there may be 1 or more integers on each line.

The `calculateSum`

method, defined below, should return the sum of all integers in the file `nums.dat`

.

As an example, let's say `nums.dat`

contains the following.

```
1 3 5 2 122
156
```

`calculateSum`

should return 289 because \(\large 1 + 3 + 5 + 2 + 122 + 156 = 289\)

Your task is to implement `calculateSum`

so that it returns the correct value for the entire file.