%token ID COMMA COLON

%%
def:    param_spec return_spec COMMA
        ;
param_spec:
             type
        |    name_list COLON type
        ;
return_spec:
             type
        |    ID COLON type
        ;
type:        ID
        ;
name:        ID
        ;
name_list:
             name
        |    name COMMA name_list
        ;
%%