# Functions
MustSettings returns Settings if err is nil and panics otherwise.
NewCtxGetter returns *CtxGetter to get Tr from context.Context.
NewDefaultFactory creates default trm.Transaction(mongo.Session).
NewSettings creates Settings.
NewTransaction creates trm.Transaction for mongo.Client.
WithSessionOpts sets up options.SessionOptions for the Settings.
WithTransactionOpts sets up options.TransactionOptions for the Settings.
# Variables
DefaultCtxGetter is the CtxGetter with settings.DefaultCtxKey.
# Structs
CtxGetter gets Tr from trm.СtxManager by casting trm.Transaction to Tr.
Settings contains settings for mongo.Transaction.
Transaction is trm.Transaction for mongo.Client.
# Type aliases
Opt is a type to configure Settings.