input: 
  def VersionControl(lines):
      """
      Implement a basic version control system in Python that keeps track of changes in the code.
      >>> vcs = VersionControl(["print('Hello, World!')"])
      >>> vcs.commit()
      >>> vcs.restore()
      """
      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()
  
output:     def __init__(self, lines):
          self.lines = lines
          self.mark = 0
          self.history = []
  
      def commit(self):
          self.mark += 1
          self.history.append(self.lines[:])
          log_file = open("log_file.txt", "a+")
          log_file.write(str(self.mark) + ": " + str(self.lines) + "\n")
          log_file.close()
  
      def restore(self):
          if self.mark > 0:
              self.mark -= 1
              self.lines = self.history[self.mark][:]