code: def getSchemaItem(self, collection, namespace, name):
          
          parent = GetSchema(self)
          if parent.targetNamespace == namespace:
              try:
                  obj = getattr(parent, collection)[name]
              except KeyError, ex:
                  raise KeyError, 'targetNamespace(%s) collection(%s) has no item(%s)'\
                      %(namespace, collection, name)
                      
              return obj
          
          if not parent.imports.has_key(namespace):
              if namespace in BUILT_IN_NAMESPACES:            
                  # built-in just return
                  # WARNING: expecting import if "redefine" or add to built-in namespace.
                  return
              
              raise SchemaError, 'schema "%s" does not import namespace "%s"' %(
                  parent.targetNamespace, namespace)
              
          # Lazy Eval
          schema = parent.imports[namespace]
          if not isinstance(schema, XMLSchema):
              schema = schema.getSchema()    
              if schema is not None:
                  parent.imports[namespace] = schema
              
          if schema is None:
              if namespace in BUILT_IN_NAMESPACES:
                  # built-in just return
                  return
              
              raise SchemaError, 'no schema instance for imported namespace (%s).'\
                  %(namespace)
                  
          if not isinstance(schema, XMLSchema):
              raise TypeError, 'expecting XMLSchema instance not "%r"' %schema
                  
          try:
              obj = getattr(schema, collection)[name]
          except KeyError, ex:
              raise KeyError, 'targetNamespace(%s) collection(%s) has no item(%s)'\
                  %(namespace, collection, name)
                      
          return obj
docs: returns object instance representing namespace, name,
             or if does not exist return None if built-in, else
             raise SchemaError.
             
             namespace -- namespace item defined in.
             name -- name of item.
             collection -- collection in parent Schema instance to search.