Method py_message

src/Exceptions.h:281–287

			: ExceptionBase(message), json(json) { }
		virtual ~InvalidJSONKey() noexcept {}
        std::string py_message() const override {
            std::string out_msg = m_message +
                " for JSON data " +
                (json.size() > 100 ? " (abbreviated): " : ": ")
                + json.substr(0, 99);
            return out_msg;
        }
	};

	/// Exception when no streams are found in the file