CatalogNode             A class for Catalogs (which may contain
                        catalogs references or datasets)
DatasetNode             A class for a single datatset reference
ServiceNode             A simple class for parsing and holdoing service
                        info
ThreddsNode             A base representation that other nodes subclass
                        from
build_xpath             Build and xpath string, possibly using the user
                        specified namespace prefix.
get_catalog             Retrieve a catalog
get_xml_ns              Retrieve the namespaces for a resource
grepl_it                Determine if a vector of names match the
                        greplargs
is_xmlNode              Test if an object inherits from xml2::xml_node
parse_node              Convert a node to an object inheriting from
                        ThreddsNode
thredds                 thredds: Crawler for Navigating THREDDS
                        Catalogs
xmlString               Convert xm2::xml_node to character
xml_children_names      Get the names of children
xml_id                  Retrieve an ID value for a node from it's
                        attributes.
