anchor.diff:    VALUE input_copy = rb_str_dup(input);
     rb_str_append(input_copy, rb_str_new2("\n%_FEATURE_END_%"));
     char *data = RSTRING_PTR(input_copy);
  -  long len = RSTRING_LEN(input_copy);
  +//  long len = RSTRING_LEN(input_copy);
  +  size_t len = RSTRING_LEN(input_copy);
     
     if (len == 0) { 
       rb_raise(rb_eGherkinLexerError, "No content to lex.");
  
positive.code:     assert(p <= pe && "data overflow after parsing execute");
      assert(lexer->content_start <= len && "content starts after data end");
      assert(lexer->mark < len && "mark is after data end");
      assert(lexer->field_len <= len && "field has length longer than the whole data");
      
      // Reset lexer by re-initializing the whole thing
      lexer_init(lexer);
  
negative.code:   lexer->content_end = 0;
    lexer->content_len = 0;
    lexer->mark = 0;
    lexer->keyword_start = 0;
    lexer->keyword_end = 0;
    lexer->next_keyword_start = 0;
  