Pushes data to the channel.

If there is a receiver, the data will be consumed immediately. Otherwise:

• If this is an non-buffered channel, this function will block until a receiver is available and the data is consumed.

• If this is a buffered channel, then:

  • If the buffer size is within the capacity, the data will be pushed to the buffer.
  • Otherwise, this function will block until there is new space for the data in the buffer.