What is returned when closing a channel using a flag in programming language?

In Go, when reading from a channel using the value and flag:

value, ok := <-ch

• If the channel is open and a value is successfully read, ok will be true.
• If the channel is closed and all values have been read, the read operation will return the zero value of the channel's type, and ok will be false.

Thus, the ok flag indicates that the channel is still open and data is available. This allows safely determining when the channel is closed and no more data will be sent.