input: Write a python function to extract the names of students from the given dictionary.
  assert extract_names({"student1" : {"name": "John", "age": 20}, "student2" : {"name": "Sam", "age": 22}, "student3" : {"name": "Alice", "age": 19}}) == ["John", "Sam", "Alice"]
  assert extract_names({"student1" : {"name": "John", "age": 20}}) == ["John"]
  assert extract_names({}) == []
output: def extract_names(students_dict):
      return [info["name"] for info in students_dict.values()]