Function is_string

include/nlohmann/json.hpp:21412–21415

@brief return whether value is a string @sa https://json.nlohmann.me/api/basic_json/is_string/

    /// @brief return whether value is a string
    /// @sa https://json.nlohmann.me/api/basic_json/is_string/
    constexpr bool is_string() const noexcept
    {
        return m_data.m_type == value_t::string;
    }

    /// @brief return whether value is a binary array
    /// @sa https://json.nlohmann.me/api/basic_json/is_binary/