input: Write a function to create a Python dictionary containing student names and their corresponding marks as key-value pairs. If no input is provided, return an empty dictionary.
  
  def create_student_marks_dict(names_and_marks=None):
      if names_and_marks is None:
          return {}
      student_marks = {}
      for i in range(0, len(names_and_marks), 2):
          student_marks[names_and_marks[i]] = names_and_marks[i+1]
      return student_marks
  
  assert create_student_marks_dict(["John", 90, "Levi", 85, "Jill", 95, "Sara", 75]) == { 
      "John" : 90, 
      "Levi" : 85, 
      "Jill" : 95, 
      "Sara" : 75
  }
  assert create_student_marks_dict(["Alice", 88, "Bob", 78]) == { 
      "Alice" : 88, 
      "Bob" : 78
  }
  assert create_student_marks_dict() == {}
  assert create_student_marks_dict(["Tom", 100]) == { 
      "Tom" : 100
  }
output: 
  def create_student_marks_dict(names_and_marks=None):
      if names_and_marks is None:
          return {}
      student_marks = {}
      for i in range(0, len(names_and_marks), 2):
          student_marks[names_and_marks[i]] = names_and_marks[i+1]
      return student_marks
  