Perhaps you should try some spelling variations:
"python using java snippets" » "python using data snippets"
"van toan hoc snippets" » "van tuan hoc snippets", "van tan hoc snippets", "van thanh hoc snippets", "van toan khoa snippets", "van van hoc snippets", "van hoa hoc snippets"
"locating bug code snippets" » "locating bung code snippets", "locating bugs code snippets", "locating bug core snippets"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("van toan hoc snippets") or ("python using java snippets"))) or ("locating bug code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("van toan hoc snippets") OR ("python using java snippets"))) OR ("locating bug code snippets")).
• Removing quotes may allow a broader search: (((( van toan hoc snippets ) or ( python using java snippets ))) or ( locating bug code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("van toan hoc snippets") or ("python using java snippets"))) or ("locating bug code snippets"))*.