code: def get(self, path_info):
          
          assert path_info["scheme"] == "local"
          path = path_info["path"]
  
          if not os.path.exists(path):
              return None
  
          actual_mtime, actual_size = get_mtime_and_size(path)
          actual_inode = get_inode(path)
  
          existing_record = self.get_state_record_for_inode(actual_inode)
          if not existing_record:
              return None
  
          mtime, size, checksum, _ = existing_record
          if self._file_metadata_changed(actual_mtime, mtime, actual_size, size):
              return None
  
          self._update_state_record_timestamp_for_inode(actual_inode)
          return checksum
docs: Gets the checksum for the specified path info. Checksum will be
          retrieved from the state database if available.
  
          Args:
              path_info (dict): path info to get the checksum for.
  
          Returns:
              str or None: checksum for the specified path info or None if it
              doesn't exist in the state database.