Suppose the internal nodes of two binary trees, T₁ and T₂ respectively, hold items that satisfy the heap-order property. Describe a method for combining these two trees into a tree T, whose internal nodes hold the union of the items in T₁ and T₂ and also satisfy the heap-order property. Your algorithms should run in time O(h₁ +h₂) where h₁ and h₂ are the respective heights of T₁ and T₂.