private async void SetBasicContent()
        {
            try
            {
                Courses.Add(new Course(
                                "Пожалуйста, подождите...",
                                "",
                                "",
                                Color.LightGray
                                )
                            );

                CoursesList.ItemsSource = Courses;

                MainHtmlParser <List <Course> > parser;

                parser = new MainHtmlParser <List <Course> >(
                    new CourseraHtmlParser(),
                    new CourseraHtmlParserSettings("courses")
                    );

                List <Course> list = new List <Course>();
                list = await parser.StartParsing();

                List <Course> list1 = new List <Course>();
                list1 = await MainApiParser.StartParsing("");

                foreach (var course in list1)
                {
                    list.Add(course);
                }

                list.Sort();

                Courses.Clear();
                foreach (var course in list)
                {
                    Courses.Add(course);
                }

                CoursesList.ItemsSource = Courses;
            }
            catch (Exception ex1)
            {
                Courses.Clear();
                Courses.Add(new Course(
                                "Что-то пошло не так!",
                                ex1.Message,
                                "",
                                Color.Pink
                                )
                            );
                CoursesList.ItemsSource = Courses;
            }
        }
        private async void SearchCourses_Tapped(object sender, EventArgs e)
        {
            try
            {
                //что происходит при поиске
                Courses.Clear();

                Courses.Add(new Course(
                                "Пожалуйста, подождите...",
                                "",
                                "",
                                Color.LightGray
                                )
                            );

                CoursesList.ItemsSource = Courses;

                MainHtmlParser <List <Course> > parser;

                parser = new MainHtmlParser <List <Course> >(
                    new CourseraHtmlParser(),
                    new CourseraHtmlParserSettings($"search?query={SearchEntry.Text.ToLower()}")
                    );

                List <Course> list = new List <Course>();

                do
                {
                    list = await parser.StartParsing();
                } while (list.Count == 0);

                List <Course> list1 = new List <Course>();
                list1 = await MainApiParser.StartParsing(SearchEntry.Text.ToLower());

                foreach (var course in list1)
                {
                    list.Add(course);
                }

                list.Sort();
                Courses.Clear();

                foreach (var course in list)
                {
                    Courses.Add(course);
                }

                if (list.Count == 0)
                {
                    Courses.Add(new Course(
                                    "",
                                    "Нет данных",
                                    "",
                                    Color.LightPink
                                    )
                                );
                }

                CoursesList.ItemsSource = Courses;
            }
            catch (Exception ex2)
            {
                Courses.Clear();
                Courses.Add(new Course(
                                "Что-то пошло не так!",
                                ex2.Message,
                                "",
                                Color.Pink
                                )
                            );
                CoursesList.ItemsSource = Courses;
            }
        }