anchor.diff:  	does nothing, but arguments will be evaluated (e.g. shell expansion)
   
   *declare-option* [-hidden] <type> <name> [<value>]::
  +	*alias* decl +
   	declare a new option, the -hidden hides the option in completion
   	suggestions (c.f. the 'options' documentation page)
   
   *set-option* <scope> <name> <value>::
  +	*alias* set +
   	change the value of an option (c.f. the 'options' documentation page),
   	note that the name of a particular buffer can be specified when the
   	target *scope* is 'buffer', e.g. set buffer=/path/to/buffer foo "bar";
  
positive.code: 	(c.f. the 'execeval' documentation page)
  
  *define-command* [<flags>] <name> <command>::
  	define a new command (c.f. the 'Declaring new commands' section below)
  
  *map* <scope> <mode> <key> <keys>::
  
negative.code: 	point to the narrowest scope available in the current context
  
  *unset-option* <scope> <name>::
  	*alias* unset +
  	unset the value of an option (c.f. the 'options' documentation page)
  
  *update-option* <scope> <name>::
  