pub fn description(&self) -> &'static str {
        match self {
            Code::Ok => "The operation completed successfully",
            Code::Cancelled => "The operation was cancelled",
            Code::Unknown => "Unknown error",
            Code::InvalidArgument => "Client specified an invalid argument",
            Code::DeadlineExceeded => "Deadline expired before operation could complete",
            Code::NotFound => "Some requested entity was not found",
            Code::AlreadyExists => "Some entity that we attempted to create already exists",
            Code::PermissionDenied => {
                "The caller does not have permission to execute the specified operation"
            }
            Code::ResourceExhausted => "Some resource has been exhausted",
            Code::FailedPrecondition => {
                "The system is not in a state required for the operation's execution"
            }
            Code::Aborted => "The operation was aborted",
            Code::OutOfRange => "Operation was attempted past the valid range",
            Code::Unimplemented => "Operation is not implemented or not supported",
            Code::Internal => "Internal error",
            Code::Unavailable => "The service is currently unavailable",
            Code::DataLoss => "Unrecoverable data loss or corruption",
            Code::Unauthenticated => "The request does not have valid authentication credentials",
        }
    }
Get description of this `Code`.
```
fn make_grpc_request() -> tonic::Code {
// ...
tonic::Code::Ok
}
let code = make_grpc_request();
println!("Operation completed. Human readable description: {}", code.description());
```
If you only need description in `println`, `format`, `log` and other
formatting contexts, you may want to use `Display` impl for `Code`
instead.
tonic/src/status.rs