Checks if the mask is a perfect hashing function for

these identifiers

Property definitions

perfect_hashing $ Perfecthashing :: phandp
	# Checks if the mask is a perfect hashing function for
	# these identifiers
	fun phandp(ids: Array[Int], mask: Int): Bool
	do
		for i in ids do
			var hv = i & mask
			if tempht[hv] == mask then
				return false
			else
				tempht[hv] = mask
			end
		end

		return true
	end
lib/perfect_hashing/perfect_hashing.nit:83,2--97,4