Open a terminal instance in a buffer By default (and currently the only option) the terminal will not be connected to an external process. Instead, input send on the channel will be echoed directly by the terminal. This is useful to disply ANSI terminal sequences returned as part of a rpc message, or similar. Note: to directly initiate the terminal using the right size, display the buffer in a configured window before calling this. For instance, for a floating display, first create an empty buffer using |nvim_create_buf()|, then display it using |nvim_open_win()|, and then call this function. Then |nvim_chan_send()| cal be called immediately to process sequences in a virtual terminal having the intended size. Parameters: ~ {buffer} the buffer to use (expected to be empty) {opts} Optional parameters. Reserved for future use. Return: ~ Channel id, or 0 on error