a
b
c

a: {
  grid-columns: 3

  1
  2
  3
  3: {
    shape: sequence_diagram
    x
    y
    # TODO x -> y
  }

  1 -> 2 -> 3

  near: center-right
}

b: {
  shape: sequence_diagram
  1 -> 2

  near: bottom-right

  2: {
    # TODO compile error grid on sequence actor?
    grid-columns: 3
    x
    y
    z
  }

  1: {
    x: {
      # TODO compile error grid in sequence (group)
      # grid-columns: 3
      u
      v
      w
    }
    y
    z
  }
}
