#checkout_line  a queue of people waiting to pay for purchases
  supertype:  waiting_line__waitingline__queue  a line of people or vehicles waiting for something
     supertype:  line.formation  a formation of people or things one behind another; "the line stretched clear around the corner"; "you must wait in a long line at the checkout counter"
        supertype:  formation_acting_as_a_unit__formation  an arrangement of people or things acting as a unit; "a defensive formation"; "a formation of planes"
           supertype:  arrangement  an orderly grouping (of things or persons)
              supertype:  group__grouping  any number of entities (members) considered as a unit
                 supertype:  collection  something gathering separated things (entities/situations)
                    supertype:  divisible_entity__divisibleentity  many classifications under this category are application-dependant
                       supertype:  entity  something that can be "involved" in a situation
                          supertype:  thing__something___T__t___3D_or_4D_thing_or_anything_else  any category (type or individual) is instance of this type; any type is also a subtype of this type
                       supertype:  divisible_thing__divisiblething
                          supertype:  thing__something___T__t___3D_or_4D_thing_or_anything_else  any category (type or individual) is instance of this type; any type is also a subtype of this type

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