number contains(container, value, flags)
Returns 1 if the array, dictionary or text contains value.
Flags:
| Flag | Description | 
|---|---|
"i" | Case-insensitive matching when comparing text (US-ASCII only) | 
"iu" | Case-insensitive matching when comparing text (Unicode, preferred) | 
"u" | Unicode-aware case folding | 
"k" | Search for a matching dictionary entry key, not value |