if condition-1
    imperative-statement-1
else
    imperative-statement-2
end-if

if condition-1
    if condition-a
        imperative-statement-1a
    else
        imperative-statement-1
    end-if
else
    if condition-a
        imperative-statement-2a
    else
        imperative-statement-2
    end-if
end-if