def add_link(self, rel, value, href=None):
links_node = self.metadata.find('<STR_LIT>')<EOL>if links_node is None:<EOL><INDENT>links_node = ioc_et.make_links_node()<EOL>self.metadata.append(links_node)<EOL><DEDENT>link_node = ioc_et.make_link_node(rel, value, href)<EOL>links_node.append(link_node)<EOL>return True<EOL>
Add a Link metadata element to the IOC.

:param rel: Type of the link.
:param value: Value of the link text.
:param href: A href value assigned to the link.
:return: True