qualif Zog(v:a) : (10 <= v)
qualif Bog(v:a, x:a) : (x <= v)

bind 0 a : {va: int | $k0[v := va][thing := thang] }
bind 1 thing : {v: int | true }
bind 2 thang : {v: int | true }

constraint:
  env [ ]
  lhs {v : int | v = 10}
  rhs {v : int | $k0}
  id 1 tag []

constraint:
  env [ ]
  lhs {v : int | v = 20}
  rhs {v : int | $k0}
  id 2 tag []

constraint:
  env [ 0 ]
  lhs {v : int | v = a}
  rhs {v : int | 10 <= v}
  id 3 tag []

wf:
  env [ 2 ]
  reft {v: int | $k0}