class Array
def into_hash(h)
unless size % 2 == 0
raise StandardError, "Expected array with even number of elements"
end
0.step(size-1, 2) { |x| h[self[x]] = self[x+1] }
h
end
end
squares = [1,1,2,3,4,9]
results = {}
p squares.into_hash(results) # => {1=>1, 2=>3, 4=>9}
[1,1,2].into_hash(results)
# StandardError: Expected array with even number of elements