def tiles_exist(self, process_tile=None, output_tile=None):
if process_tile and output_tile:<EOL><INDENT>raise ValueError("<STR_LIT>")<EOL><DEDENT>if process_tile:<EOL><INDENT>return any(<EOL>path_exists(self.get_path(tile))<EOL>for tile in self.pyramid.intersecting(process_tile)<EOL>)<EOL><DEDENT>if output_tile:<EOL><INDENT>return path_exists(self.get_path(output_tile))<EOL><DEDENT>
Check whether output tiles of a tile (either process or output) exists.

Parameters
----------
process_tile : ``BufferedTile``
    must be member of process ``TilePyramid``
output_tile : ``BufferedTile``
    must be member of output ``TilePyramid``

Returns
-------
exists : bool