Perhaps you should try some spelling variations:
"python missing data snippets" » "python using data snippets"
"locating bugs code snippets" » "locating bug code snippets"
"o viet da snippets" » "o viet dao snippets", "o viet dat snippets", "o viet ha snippets", "so viet da snippets", "hoc viet da snippets"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("o viet da snippets") or ("python missing data snippets"))) or ("locating bugs code snippets"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("o viet da snippets") OR ("python missing data snippets"))) OR ("locating bugs code snippets")).
• Removing quotes may allow a broader search: (((( o viet da snippets ) or ( python missing data snippets ))) or ( locating bugs code snippets )).
• Adding a wildcard symbol may retrieve word variants: (((("o viet da snippets") or ("python missing data snippets"))) or ("locating bugs code snippets"))*.