e, if it has to
 instantiate the Parser itself , then this function will cache that Parser
 in the internal <code>PARSER_CACHE</code>.
<P>
<DD><DL>
<DT><B>Parameters:</B><DD><CODE>id</CODE> - The string extension ID (e.g.,
        "org.apache.nutch.parse.rss.RSSParser",
        "org.apache.nutch.parse.rtf.RTFParseFactory") of the <A HREF="../../../../org/apache/nutch/parse/Parser.html" title="interface in org.apache.nutch.parse"><CODE>Parser</CODE></A>
        implementation to return.
<DT><B>Returns:</B><D