anchor.diff:  	| attribute_instance* system_task_enable
   	| attribute_instance* task_enable
   	| attribute_instance* wait_statement
  +	| in_module_compiler_directive
   	;
   
   statement_or_null
  
positive.code: 	;
  
  ifdef_group_of_lines
  	: non_port_module_item*
  	;
  
  ifndef_group_of_lines
  	: non_port_module_item*
  	;
  
  elsif_group_of_lines
  	: non_port_module_item*
  	;
  
  else_group_of_lines
  	: non_port_module_item*
  	;
  
  // 19.5 `include
  
negative.code: 	| endkeywords_directive
  	;
  
  in_module_compiler_directive
  	:/* text_macro_definition
  	| text_macro_usage
  	|*/ conditional_compilation_directive
  	;
  
  post_module_compiler_directive
  	: endcelldefine_compiler_directive
  	| default_nettype_compiler_directive
  	| conditional_compilation_directive
  	| undefine_compiler_directive
  	| resetall_compiler_directive
  	| nounconnected_drive_compiler_directive
  	| keywords_directive
  	| endkeywords_directive
  	;
  
  // 19.1 `celldefine and `endcelldefine
  