Searches an ENTITY's attribute list for an ATTRIB of a given type, starting
at a given attribute.
Role: Searches an ENTITY's attribute list for an ATTRIB of a given
type, starting at the given attribute. All attribute type codes are guaranteed unique for
any run of ACIS. If no matching ATTRIB is found, NULL is returned.
Use find_leaf_attrib to find the first instance of an attribute that matches your search criteria.
Use find_next_leaf_attrib iteratively to search for the next attribute that meets your search criteria.