private void button1_Click(object sender, EventArgs e)
        {
            listView1.Items.Clear();
            UserData data = ForumApiClient.GetUser(textBox1.Text);

            listView1.Items.Add(data.id.ToString());
            listView1.Items.Add(data.firstname);
            listView1.Items.Add(data.lastname);
        }
        private void button2_Click(object sender, EventArgs e)
        {
            listView2.Items.Clear();
            UsersData data = ForumApiClient.GetUsers();

            foreach (List item in data.list)
            {
                ListViewItem lvitem = new ListViewItem();
                lvitem.SubItems.Add(item.id.ToString());
                lvitem.SubItems.Add(item.firstname);
                lvitem.SubItems.Add(item.lastname);
                listView2.Items.Add(lvitem);
            }
        }