Referencing canvas variables with outputs of other variables

[dreynolds (Dan)]

I have multiple variables defined that have the number of hosts a department should have:
hr_hosts: 35, it_hosts:45, acct_hosts:5

I'm running a query to pull host scans, which includes the department names as a column "hr", "it", "acct"

I would like to return the value of "hr_hosts", "it_hosts", and "acct_hosts" in a new column.
I successfully output the variable names, but I'm not sure how to force canvas to actually reference the variables.

mapColumn name='departmentCounts' expression={ getCell department | string "var " { context } "_hosts"}