Goal:
  
  ============================
   (max None None = None)


DEBUG:Going to execute:
reflexivity
Level 1: Backtrace:

In environment
z : Z
Unable to unify "Some z" with "max (Some z) (Some z)".
Level 0: Backtrace:

In environment
z : Z
Unable to unify "Some z" with "max (Some z) (Some z)".