[M2Doc] Variable declaration with 'let' is final?

is there a way to declare a variable with e.g. ‘let’ and to assign other values later to this variable? I’m doing some iteration over model elements and would like to do some calculation in each iteration (e.g. a simple counter). Having read that ‘let’ in AQL is final, I assume that the M2Doc is also final?
My workaround was using a template and recursion (i.e. call the template with an initial value for a counter and the template will call itself with an increased counter). This works for this easy example but does not feel right
Kind regards

Copyright © Eclipse Capella, the Eclipse Capella logo, Eclipse and the Eclipse logo are Trademarks of The Eclipse Foundation.