Compartments:
	size of sales force
	Initial value = 50
	Rate of change =  + new_hires - departures
Flows:
	new hires = hiring_fraction*(budgeted_size_of_sales_force-size_of_sales_force)
	departures = size_of_sales_force*exit_rate
Variables:
	annual revenue in millions = widget_sales*widget_price/1000000
	budgeted size of sales force = sales_dept_budget*1000000/average_salary
	effectiveness in widgets per day = graph(size_of_sales_force)
	sales dept budget = fraction_to_sales*annual_revenue_in_millions
	widget sales = size_of_sales_force*effectiveness_in_widgets_per_day*365
Parameters:
	average salary = 25000
	exit rate = 0.2
	fraction to sales = 0.5
	hiring fraction = 1
	widget price = 100