code: def visit_module(self, node):
          
          if not node.file_stream:
              # failed to open the module
              return
          text = node.file_stream.read()
          self._checkCopyright(text, node)
          if not isTestModule(node.name) and moduleNeedsTests:
              self._checkTestReference(text, node)
docs: A interface will be called when visiting a module.
  
          @param node: node of current module