This might be a very simple and easy question to answer, perhaps not.

To concatenate a string (by appending/right concat.) in php you use:

$a = "a";

$a .= "b";
//The value will be: "ab"

How do I do this, but the other way around?

Ej.:

$a = "a";

$a ???? "b";
//I NEED the value to be: "ba"