anchor.diff:  arithmetic_primary
   	: numeric_literal
   	| LPAREN simple_arithmetic_expr RPAREN
  -	| functions_returning_numerics
  -	//| attr_field
  +	| funcs_returning_numerics
   	;
   
   string_expr
  
positive.code: 
  string_primary
  	: string_literal
  	| functions_returning_strings
  	//| attr_field
  	;
  
  datetime_expr
  	: functions_returning_datetime
  	//| attr_field
  	;
  
  boolean_expr
  	: boolean_literal
  	//| attr_field
  	;
  
  functions_returning_numerics
  	: keyLENGTH LPAREN string_primary RPAREN
  	| keyABS LPAREN simple_arithmetic_expr RPAREN
  	| keyMOD LPAREN simple_arithmetic_expr COMMA simple_arithmetic_expr RPAREN
  	;
  
  functions_returning_datetime
  	: keyCURRENT_DATE
  	| keyCURRENT_TIME
  	| keyCURRENT_TIMESTAMP;
  
  functions_returning_strings
  	: keyCONCAT LPAREN string_primary COMMA string_primary RPAREN
  	| keySUBSTRING LPAREN string_primary COMMA simple_arithmetic_expr COMMA simple_arithmetic_expr RPAREN
  	| keyTRIM LPAREN string_primary RPAREN
  
negative.code: attr_field
  	: ID;
  		
  string_literal
  	: QUOTED;
  	
  