#single_file__file__Indian_file  a line of persons or things ranged one behind the other
  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"
  subtype:  #snake_dance.single_file__snakedance  a group advancing in a single-file serpentine path
  subtype:  #column  a line of (usually military) units following one after another

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