getExportedValue(ns, name)
getNamespace(name)
getNamespaceExports(ns)
getNamespaceImports(ns)
getNamespaceName(ns)
getNamespaceUsers(ns)
getNamespaceVersion(ns)getExportedValue returns the value of the exported variable
  name in namespace ns.  getNamespace returns the environment representing the name
  space name.  The namespace is loaded if necessary.
  getNamespaceExports returns a character vector of the names
  exported by ns.
  getNamespaceImports returns a representation of the imports
  used by namespace ns.  This representation is experimental
  and subject to change.
  getNamespaceName and getNamespaceVersion return the name
  and version of the namespace ns.
  getNamespaceUsers returns a character vector of the names of
  the namespaces that import namespace ns.
loadNamespace for more about namespaces.