input: Write a function to print a formatted table of grades for a given set of students.
  
  assert print_grade_table([
      {'name': "John", 'grade': 92},
      {'name': "Alice", 'grade': 95},
      {'name': "Bob", 'grade': 87}
  ]) == None
  
  assert print_grade_table([]) == None
output: def print_grade_table(students):
      if not students:
          return
      print("Name   | Grade")
      print("--------------")
      for student in students:
          print(f"{student['name']:6} | {student['grade']}")