What is the point of 'else' after a block which ends in 'return'

Is there an advantage to having an 'else' following a block which ends with a 'return' or is it simply out of habit

int foo (int a)
{
    if(a==0)
    {
        return false;
    }
    else
        if(a==1)
        {
            return true;
        }
        else
        {
        }
    return -1;
}

just curious

This is purely a style choice, or perhaps a misunderstanding that else is required for every if.

If all the if blocks contain return, there's no technical difference between putting the remaining code in a final else block or putting it after the final else if block in the chain; the same code should be generated. And an empty else block has no effect at all.

Some programmers may prefer to use the else block for stylistic reasons, it makes the parallel structure clear.

There's also no technical reason to use else if when all the if blocks return. There are some proponents of "else-less" programming who would write the above function as

int foo (int a)
{
    if(a==0)
    {
        return false;
    }
    if(a==1)
    {
        return true;
    }
    return -1;
}

On the other hand, many programmers prefer a chain of else if to make it clear that these are mutually exclusive conditions. Then you don't have to look into the bodies to see that they all return.