Created nlohmann::basicjson::front (markdown)

nlohmann::basicjson::front.md

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+```cpp
+reference front();
+const_reference front() const;
+```
+
+## Description
+
+Returns a reference to the first element in the container. Calling `front` on an empty container is undefined.
+
+For a JSON container `c`, the expression `c.front()` is equivalent to `*c.begin()`.
+
+## Parameters
+
+None.
+
+## Return value
+
+Reference to the first 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
+
+- [**back**](https://github.com/nlohmann/json/wiki/nlohmann::basicjson::back)<br>
+  access the last element