code: def add(self, path):
          
          
          # sys.path always has absolute paths.
          path = os.path.abspath(path)
          
          # It must exist.
          if not os.path.exists(path):
              return
          
          # It must not already be in sys.path.
          if path in sys.path:
              return
  
          if self.index is not None:
              sys.path.insert(self.index, path)
              self.index += 1
          else:
              sys.path.append(path)
docs: Add the given path to the decided place in sys.path