input: Write a function `implement_version_control` that implements a basic version control system in Python that keeps track of changes in the code. The function should return an instance of the `VersionControl` class which has methods to commit changes and restore to a previous commit. If the log file does not exist, it should create it.
  
  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 implement_version_control(["a", "b", "c"]).commit() is None
  assert implement_version_control(["a", "b", "c"]).restore() is None
  assert implement_version_control([]).commit() is None
  assert implement_version_control([]).restore() is None
output: def implement_version_control(lines):
      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) + "\n")
              log_file.close()
   
          def restore(self):
              log_file = open("log_file.txt", "r")
              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])
              log_file.close()
      
      return VersionControl(lines)