This animation shows how mergesort works. First, we devide the array to two parts, then to another
two parts, until we get parts with one element only. These 1-element parts are sorted. Next, we
merge these 1-element parts to a 2-element part. When we have two sorted 2-element parts, we
merge them to a 4-element part. Finally, we merge the two 4-element parts to get the sorted array.
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