Expand description
Detecting lang items.
Language items are items that represent concepts intrinsic to the language itself. Examples are:
- Traits that specify “kinds”; e.g., 
Sync,Send. - Traits that represent operators; e.g., 
Add,Sub,Index. - Functions called by the compiler itself.
 
Functions§
- required
 - Returns 
trueif the specifiedlang_itemmust be present for this compilation.