//==============================================
File: slim_park_beg.txt
Args: COLOR=red NAME= --lenient

a_color=$(COLOR)
b_color=$(COLOR=green)
c_color=$(COLOR:=green)

a_name=$(NAME)
b_name=$(NAME=fred)
c_name=$(NAME:=fred)

a_role=$(ROLE)
b_role=$(ROLE=rescue)
c_role=$(ROLE:=scout)

a_color=$(COLOR), name=$(NAME), role=$(ROLE)
b_color=$(COLOR=green), name=$(NAME), role=$(ROLE)
c_color=$(COLOR=green), name=$(NAME=fred), role=$(ROLE)
d_color=$(COLOR=green), name=$(NAME:=fred), role=$(ROLE)

a_color=$(COLOR), color2=$(COLOR), name=$(NAME=gabe), role=$(ROLE), color3=$(COLOR)
b_color=$(COLOR), guy=$(NAME=ben), gal=$(NAME:=eve)
c_guy=$(NAME=ben), gal=$(NAME:=eve), dude=$(NAME=fin)
d_role=$(ROLE:=scout), guy=$(NAME=ben), color=$(COLOR:=pink), dude=$(NAME:=fin)

//----------------------------------------------
File: slim_park_tar.txt

a_color=red
b_color=red
c_color=red

a_name=
b_name=
c_name=fred

a_role=$(ROLE)
b_role=rescue
c_role=scout

a_color=red, name=, role=$(ROLE)
b_color=red, name=, role=$(ROLE)
c_color=red, name=, role=$(ROLE)
d_color=red, name=fred, role=$(ROLE)

a_color=red, color2=red, name=, role=$(ROLE), color3=red
b_color=red, guy=, gal=eve
c_guy=, gal=eve, dude=
d_role=scout, guy=, color=red, dude=fin