input: Write a function to implement a basic version control system in Python that keeps track of changes in the code. The function should include a class named VersionControl with an `__init__` method that initializes the lines of code and a mark for the version, a `commit` method that saves the current version of the code to a log file, and a `restore` method that restores the code to the previous version based on the mark.
  
  
  class VersionControl:
      def __init__(self, lines):
          self.lines = lines
          self.mark = 0
   
      def commit(self):
          self.mark += 1
          log_file = open("log_file.txt", "a+")
          log_file.write(str(self.mark) + ": " + str(self.lines))
          log_file.close()
   
      def restore(self):
          log_file = open("log_file.txt", "r")
          lines = log_file.readlines()
          to_mark = self.mark-1
   
          self.lines = lines[to_mark]
          log_file.close()
  
  assert VersionControl(["print('Hello')"]).commit() == None
  assert VersionControl(["print('Hello')", "print('World')"]).commit() == None
  vc = VersionControl(["print('Hello')", "print('World')"])
  vc.commit()
  vc.restore()
  assert vc.lines == "print('Hello')", "print('World')"
  assert VersionControl([]).commit() == None
  assert VersionControl([]).restore() == None
  
output: class VersionControl:
      def __init__(self, lines):
          self.lines = lines
          self.mark = 0
   
      def commit(self):
          self.mark += 1
          with open("log_file.txt", "a+") as log_file:
              log_file.write(f"{self.mark}: {self.lines}\n")
   
      def restore(self):
          with open("log_file.txt", "r") as log_file:
              lines = log_file.readlines()
              to_mark = self.mark - 1
              if to_mark >= 0 and to_mark < len(lines):
                  self.lines = eval(lines[to_mark].split(": ", 1)[1])
              else:
                  self.lines = []