A platform is positioned above the conveyor and is capable of alternatingly moving in either one of a first direction, substantially similar to the direction of motion of the conveyor, and {HEAD ~ a second direction}, substantially opposite to {TAIL ~ the direction} of motion of the conveyor 
substantially opposite to
A platform is positioned above the conveyor and is capable of alternatingly moving in either one of a first direction , substantially similar to the direction of motion of the conveyor , and { HEAD ~ a second direction } , substantially opposite to { TAIL ~ the direction } of motion of the conveyor
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