anchor.diff:  
   statement		: if_statement
   				| for_loop
  +				| while_loop
   				| expression ';'
  -				| 'return' expression ';'
  +				| keyword expression ';'
   				;
   
   if_statement	: 'if' expression block ('else if' expression block)* ('else' block)? ;
   
  -for_loop		: 'for' (definition | ID) 'in' expression (expression ';' | block) ;
  +for_loop		: 'for' (definition | name) 'in' expression (expression ';' | block) ;
  +
  +while_loop		: 'while' expression (expression ';' | block) ;
   
   expression		: definition
   				| assignment
  
positive.code: 
  operand			: '*' | '/' | '+' | '-' ;
  
  unary_operand	: '!' | '-' ;
  
  type			: 'int' | 'uint' | 'float' | 'bool' | 'byte' | 'fn' 
  				| 'string' | 'list' | 'table' | 'meta' | ID
  				;
  
  atom			: INT
  
negative.code: 
  argument_list	: definition (',' definition)* ;
  
  table_access	: name '[' STRING ']' ;
  
  type_list		: type (',' type)* ;
  
  