Trace class:
  Stream class (ID 0):
    Supports packets: Yes
    Packets have beginning default clock snapshot: No
    Packets have end default clock snapshot: No
    Supports discarded events: No
    Supports discarded packets: No
    Event class `ev` (ID 0):
      Payload field class: Structure (3 members):
        x: Unsigned integer (8-bit, Base 10)
        y: Structure (2 members):
          a: Unsigned integer (8-bit, Base 10)
          b: Static array (Length 0):
            Element: Unsigned integer (8-bit, Base 10)
        z: Unsigned integer (8-bit, Base 10)

{Trace 0, Stream class ID 0, Stream ID 0}
Stream beginning:
  Trace:
    Stream (ID 0, Class ID 0)

{Trace 0, Stream class ID 0, Stream ID 0}
Packet beginning

{Trace 0, Stream class ID 0, Stream ID 0}
Event `ev` (Class ID 0):
  Payload:
    x: 1
    y:
      a: 5
      b: Empty
    z: 9

{Trace 0, Stream class ID 0, Stream ID 0}
Packet end

{Trace 0, Stream class ID 0, Stream ID 0}
Stream end