Lookup of Consumables in RTI Module

[thewati]

Look-up of item codes is done individually across the module rti.py. It would be more efficient to do the look-up in one function and then just call it from different points in the code. The following needs to be done to complete this:

• Create a function called look_up_consumable_item_codes which will lookup the item codes used in the HSI for RTI
• Call specific item codes required for a particular HSI using the function
• Run test_rti.py to make sure all tests pass