Goal:
    m : Z
  ============================
   ({True} + {False})


DEBUG:Going to execute:
left; constructor
Level 0: Backtrace:

The type has no constructors.
Level 0: Backtrace:

The type has no constructors.
Level 1: Backtrace:

The type has no constructors.
Level 0: Backtrace:

The type has no constructors.
Level 0: Backtrace:

The type has no constructors.