anchor.diff:  #    TOKANCESTOR  LPAREN clock1 COMMA clock2 RPAREN SEMICOLON
   #    TOKSAME_FAMILY  LPAREN clock1 COMMA clock2 RPAREN SEMICOLON
   
  +    rule provisos_clause:
  +        TOKPROVISOS param_list
  +
       rule import_declaration:
           TOKIMPORT
           ( TOKBDPI [ VAR  EQUAL ]
  
positive.code:     rule module_declaration:
          TOKMODULE [ LBRACKET assign_value RBRACKET ] ( VAR | TYPEVAR argument_list )
          LPAREN [ module_param (COMMA module_param)* ] RPAREN
          [ provisos_clause ]
          SEMICOLON
          [
              module_item
              TOKENDMODULE [ COLON VAR]
  
negative.code:     rule function_name:
          VAR | function_operator
  
      rule import_arg:
          ( VAR | LPAREN VAR (COMMA VAR)* RPAREN )
  
  