code: def build_global(self, global_node):
  
          
          config_block_lines = self.__build_config_block(
              global_node.config_block)
          return config.Global(config_block=config_block_lines)
docs: parse `global` section, and return the config.Global
  
          Args:
              global_node (TreeNode):  `global` section treenode
  
          Returns:
              config.Global: an object