Function is_array

! @brief return whether value is an array This function returns true if and only if the JSON value is an array. @return `true` if type is array, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_array()` for all JSON types.,is_array} @since version 1.0.0