In the Fluent function example provided, it will help explaining different parts and provide the final output of the three-part formula and which part feeds to next part . In the given example, what is the first argument, what is the left side of the dot-invocation?

In section 13.1 of Developer's Guide, the Fluent function concept is detailed with the following example as noted below

A fluent function means that it can be invoked using dot-notation (.), and the first argument to the function will be provided by the value of the left-side of the dot-invocation at that point. For example:

define "Diabetes Conditions":
[Condition: "Diabetes Mellitus"]

define "Confirmed and Active or Recurring Diabetes Conditions":
Conditions.confirmed().activeOrRecurring()

It will be helpful if an explanation of the outcome is provided.  

The related page is here:

https://cql.hl7.org/2020May/03-developersguide.html#fluent-functions

Additional contact persons to discuss this:

Hafsa Subhan

Mitra Biglari