code: def paths_to_str(paths, format_kwargs={}, delimiter=os.pathsep, asset_paths=False,
                   check_paths=False):
      
      if not paths:
          return ''
      if isinstance(paths, str):
          paths = paths.split(delimiter)
      processed_paths = []
      for path in paths:
          original = path
          path = path.format_map(format_kwargs)
          if not os.path.isabs(path):
              if asset_paths and ':' in path:
                  try:
                      path = asset_path(path)
                  except ValueError:
                      path = None
          if path is not None and os.path.isdir(path):
              processed_paths.append(path)
          elif check_paths:
              f = locals()
              printer.warning('Path does not exist: {path} (from {original})'.format_map(f))
      return delimiter.join(processed_paths)
docs: Convert ``paths`` to a single string.
  
      Args:
          paths (str|list): A string like "/a/path:/another/path" or
              a list of paths; may include absolute paths and/or asset
              paths; paths that are relative will be left relative
          format_kwargs (dict): Will be injected into each path
          delimiter (str): The string used to separate paths
          asset_paths (bool): Whether paths that look like asset paths
              will be converted to absolute paths
          check_paths (bool): Whether paths should be checked to ensure
              they exist