Perhaps you should try some spelling variations:
"coder coder in challenging problem" » "coder coder in charging problem" (Expand search), "coder coder in chattering problem" (Expand search), "coder coder in challenging proposal" (Expand search), "coder coder _ challenging problem" (Expand search), "coder coder the challenging problem" (Expand search), "coder coder in changing problem" (Expand search), "coder decoder in challenging problem" (Expand search), "code code in challenging problem" (Expand search), "decoder codec in challenging problem" (Expand search), "coder code in challenging problem" (Expand search), "coder codes in challenging problem" (Expand search), "coder poder in challenging problem" (Expand search)
"in python python python programming" » "in pythons python python programming" (Expand search), "in piton python python programming" (Expand search), "in pitons python python programming" (Expand search), "_ python python python programming" (Expand search)

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("coder coder in challenging problem") OR ("in python python python programming"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"coder coder in challenging problem\") OR (\"in python python python programming\"))*".
• Removing quotes may allow a broader search: (( coder coder in challenging problem ) OR ( in python python python programming ))*.