2. P: T
3. a: array(T)
0
sum(if P(a[i])
1 else 0 fi | i < |a|)2. P: T
3. a: array(T)
sum(if P(a[i]) 1 else 0 fi | i < |a|) < |a|+1
T:Type, P:(T), a:array(T). array-count(v.P(v);a) 
(|a|+1)
| 1 | 1. T: Type 2. P: T 3. a: array(T) 0sum(if P(a[i]) 1 else 0 fi | i < |a|) | 1 step |
| 2 | 1. T: Type 2. P: T 3. a: array(T) sum(if P(a[i]) 1 else 0 fi | i < |a|) < |a|+1 | 1 step |
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