แสดงชื่อครูที่สอนอย่างน้อยสองรายวิชา
Show names of teachers that teach at least two courses.
df_teacher = pd.DataFrame(columns=['Name', 'Teacher_ID'])
df_course_arrange = pd.DataFrame(columns=['Teacher_ID'])
df_course_arrange['Teacher_ID'].value_counts()[df_course_arrange['Teacher_ID'].value_counts() >= 2].index.to_frame('Teacher_ID').merge(df_teacher, on='Teacher_ID')['Name']