For to do sth

hello

A couple of times I came across an expression "for to do something" appearing in contexts where just "to do sth" would be more suitable I think. Take for example a line from The Carter Family song Can the Circle Be Unbroken. It says:

I was standing by my window
On a cold and cloudy day
When I saw that hearse come a-rolling
For to carry my mother away

Ok I know that some rules do not apply in poetry but I'm positive I saw this 'structure' in other contexts too.
I failed to find it in my dictionaries so could someone please direct me to an online source on this topic or explain it to me? Is it archaic, informal, etc..

Thank you,
Michal