input: Write a python function to extract the names of students who scored more than 80 marks.
  assert extract_top_students([{'name': 'John', 'mark': 75}, {'name': 'Alex', 'mark': 92}, {'name': 'Tiffany', 'mark': 83}, {'name': 'Eddie', 'mark': 67}]) == ['Alex', 'Tiffany']
  assert extract_top_students([{'name': 'John', 'mark': 85}, {'name': 'Alex', 'mark': 60}, {'name': 'Tiffany', 'mark': 90}, {'name': 'Eddie', 'mark': 95}]) == ['John', 'Tiffany', 'Eddie']
  assert extract_top_students([{'name': 'John', 'mark': 75}, {'name': 'Alex', 'mark': 55}, {'name': 'Tiffany', 'mark': 65}, {'name': 'Eddie', 'mark': 67}]) == []
output: def extract_top_students(students):
      return [student['name'] for student in students if student['mark'] > 80]