nested indentation of lines

Question

I am trying to figure out how to configure proper indentation when writing an algorithm in LaTex.

The algorithm code should look like:

Let a = 0
let b = 1
if (a > b)
    do action 1
else if (a = b)
    do action 2
else 
    do action 3
all done

I could have more than one level of indentation involved in the algorithms, so it needs to be a flexible solution.

Any suggestions are greatly appreciated.