DBMS_METADATA: How to transform a DDL "create sequence scott.seq" into it an xml like dbms_metadata

Dear all,
DBMS_METADATA: How to transform an sql "create sequence scott.seq" into it an xml like dbms_metadata without creating the objects?

From an DDL SQL Statement, it's needed to get it's xml represenetation in order to be able to compare this DDL with an already existing objects.

SQL  := 'create sequence scott.seq' ;
XML := '
<?xml version="1.0"?><ROWSET><ROW>
  <SEQUENCE_T>
 <VERS_MAJOR>1</VERS_MAJOR>
 <VERS_MINOR>0</VERS_MINOR>
 <OBJ_NUM>84822</OBJ_NUM>
 <SCHEMA_OBJ>
  <OBJ_NUM>84822</OBJ_NUM>
  <OWNER_NUM>152</OWNER_NUM>
  <OWNER_NAME>SCOTT</OWNER_NAME>
  <NAME>SEQ</NAME>
  <NAMESPACE>1</NAMESPACE>
  <TYPE_NUM>6</TYPE_NUM>
  <TYPE_NAME>SEQUENCE</TYPE_NAME>