||Component type: function
template <class ForwardIterator>
inline ForwardIterator rotate(ForwardIterator first, ForwardIterator middle,
Rotate rotates the elements in a range. That is, the element pointed
to by middle is moved to the position first, the element pointed
to by middle + 1 is moved to the position first + 1, and so on.
One way to think about this operation is that it exchanges the two
ranges [first, middle) and [middle, last). Formally, for every
integer n such that 0 <= n < last - first, the element
*(first + n) is assigned to *(first + (n + (last - middle)) % (last
- first)). Rotate returns first + (last - middle).
Defined in the standard header algorithm, and in the nonstandard
backward-compatibility header algo.h.
Requirements on types
[first, middle) is a valid range.
[middle, last) is a valid range. 
Linear. At most last - first swaps are performed. 
char alpha = "abcdefghijklmnopqrstuvwxyz";
rotate(alpha, alpha + 13, alpha + 26);
// The output is nopqrstuvwxyzabcdefghijklm
It follows from these two requirements that [first, last) is
a valid range.
Rotate uses a different algorithm depending on whether its
arguments are Forward Iterators, Bidirectional Iterators,
or Random Access Iterators. All three algorithms, however,
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