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var empty struct{}
// Init array size 9
row_set := [9]map[byte]struct{}{}
// Init maps in array
for i:=0; i<9; i++ {
row_set[i] = make(map[byte]struct{})
}
// Add value
row_set[0]['a'] = empty
// Check if exists
_, ok := row_set[0]['a']
// Remove value
delete(row_set[0], 'a')