Like Connection.query, but takes a filename to load a query from.

def query_file(self, path, fetchall=False, **params):
        """Like Connection.query, but takes a filename to load a query from."""

        # If path doesn't exists
        if not os.path.exists(path):
            raise IOError("File '{}' not found!".format(path))

        # If it's a directory
        if os.path.isdir(path):
            raise IOError("'{}' is a directory!".format(path))

        # Read the given .sql file into memory.
        with open(path) as f:
            query = f.read()

        # Defer processing to self.query method.
        return self.query(query=query, fetchall=fetchall, **params)