def contour_data
      x, y, z = coords
      return [x, y, z].transpose.flatten.join("\\")
    end
def contour_data
      x, y, z = coords
      return [x, y, z].transpose.flatten.join("\\")
    end
Creates a string where the coordinates of this contour are packed to a
 string in the format used in the Contour Data DICOM Element (3006,0050).

 @return [String] an encoded coordinate string (or an empty string if no coordinates are associated)