removes the passed in file from the connected triplestore

        args:
            filename: the filename to remove

def drop_file(self, filename, **kwargs):
        """ removes the passed in file from the connected triplestore

        args:
            filename: the filename to remove
        """
        log.setLevel(kwargs.get("log_level", self.log_level))
        conn = self.__get_conn__(**kwargs)
        result = conn.update_query("DROP GRAPH %s" % \
                                   getattr(__NSM__.kdr, filename).sparql,
                                   **kwargs)
        # Remove the load time from the triplestore
        conn.update_query("""
                DELETE
                {{
                   GRAPH {graph} {{ ?file dcterm:modified ?val }}
                }}
                WHERE
                {{
                    VALUES ?file {{ kdr:{file} }} .
                    OPTIONAL {{
                        GRAPH {graph} {{?file dcterm:modified ?val }}
                    }}
                }}""".format(file=filename, graph="kdr:load_times"),
                **kwargs)
        self.loaded.remove(filename)
        log.warning("Dropped file '%s' from conn %s", filename, conn)
        return result