def new_pattern(self, id_, name, rows=None):
if rows is None:<EOL><INDENT>rows = self.new_row_collection()<EOL><DEDENT>return self._spec.new_pattern(id_, name, rows, self)<EOL>
Create a new knitting pattern.

        If rows is :obj:`None` it is replaced with the
        :meth:`new_row_collection`.