Check whether the module has copyright header.

        @param text: codes of the module
        @param node: node of the module

def _checkCopyright(self, text, node):
        """
        Check whether the module has copyright header.

        @param text: codes of the module
        @param node: node of the module
        """
        if not re.search(br"%s\s*\n\s*%s" % self.commentsCopyright, text):
            self.add_message('W9001', node=node)