input: Write a function to print a formatted table of grades for a given set of students. The function should accept a list of dictionaries where each dictionary contains a student's 'name' and 'grade'. If the list is empty, the function should print nothing.
  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
      for student in students:
          print(f"{student['name']}: {student['grade']}")