code: private function parseImplementsInterfaces()
      {
          $types = [];
          if ($this->lexer->token->value === 'implements') {
              $this->lexer->advance();
              // Optional leading ampersand
              $this->skip(Token::AMP);
              do {
                  $types[] = $this->parseNamedType();
              } while ($this->skip(Token::AMP) ||
              // Legacy support for the SDL?
              (! empty($this->lexer->options['allowLegacySDLImplementsInterfaces']) && $this->peek(Token::NAME))
              );
          }
  
          return $types;
      }
docs: ImplementsInterfaces :
  - implements `&`? NamedType
  - ImplementsInterfaces & NamedType
  
  @return NamedTypeNode[]