def require_images():
if (not image_exists('<STR_LIT>') or<EOL>not image_exists('<STR_LIT>') or<EOL>not image_exists('<STR_LIT>')):<EOL><INDENT>raise DatacatsError(<EOL>'<STR_LIT>')<EOL><DEDENT>
Raises a DatacatsError if the images required to use Datacats don't exist.