Make it possible to use variables as operation parameters

In order to be able to create more real-life test scenarios I would like to ask to make it possible to use variables as operation parameters.
For example, a sample scenario is to make a user to order a random number of items.
The idea of how to implement this is to record the ordering of one item, add the Loop operation to the scenario and move relevant requests into the loop.
The current problem is that the loop can repeat only the fixed number of iterations.
Expected improvement is that it will be possible to create a project variable of random type in the range, say, from 1 to 10 and reference this variable as a loop counter.
The expected result is that every virtual user will order random number of items in the range between 1 and 10.

Thanks,
/Alex
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