code: def autoblend(self):
          
          namespaces = self.namespaces.keys()
          for s in self.children:
              for ns in namespaces:
                  tns = s.root.get('targetNamespace')
                  if tns == ns:
                      continue
                  for imp in s.root.getChildren('import'):
                      if imp.get('namespace') == ns:
                          continue
                  imp = Element('import', ns=Namespace.xsdns)
                  imp.set('namespace', ns)
                  s.root.append(imp)
          return self
docs: Ensure that all schemas within the collection
          import each other which has a blending effect.
          @return: self
          @rtype: L{SchemaCollection}