Created nlohmann::basicjson::back (markdown)

nlohmann::basicjson::back.md

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+```cpp
+reference back();
+const_reference back() const;
+```
+
+## Description
+
+Returns a reference to the last element in the container. Calling `back` on an empty container is undefined.
+
+For a JSON container `c`, the expression `return c.back();` is equivalent to `{ auto tmp = c.end(); --tmp; return *tmp; }`.
+
+## Parameters
+
+None.
+
+## Return value
+
+Reference to the last element. In cast of number, string, or boolean values, a reference to the value is returned.
+
+## Complexity
+
+Constant.
+
+## Exceptions
+
+`std::out_of_range` when called on null value.
+
+## See also
+
+- [**front**](https://github.com/nlohmann/json/wiki/nlohmann::basicjson::front)<br>
+  access the first element