Background returns a non-nil, empty Context.

TODO returns a non-nil, empty Context.

WithCancel returns a copy of parent with a new Done channel.

WithDeadline returns a copy of the parent context with the deadline adjusted to be no later than d.

WithTimeout returns WithDeadline(parent, time.Now().Add(timeout)).

WithValue returns a copy of parent in which the value associated with key is val.

Canceled is the error returned by Context.Err when the context is canceled.

DeadlineExceeded is the error returned by Context.Err when the context's deadline passes.

A Context carries a deadline, a cancelation signal, and other values across API boundaries.

A CancelFunc tells an operation to abandon its work.