Create a stacked channel with the given mode (i.e. readable/writable) and which is implemented using the given ensemble-like command (or command prefix; it may include multiple words).
chan create mode cmdPrefix
[ To do: document the API expected to be used by the implementation command ]
Required Subcommands
cmdPrefix initialize channelId mode - Must be supported. Must return list of all subcommands supported (i.e., minimally initialize, finalize and watch).
cmdPrefix finalize channelId - Must be supported. Must not access the channel in any way.
cmdPrefix watch channelId eventSpec - Must be supported. Interacts with chan postevent.
Optional Subcommands
cmdPrefix read channelId count - Non-readable channels do not need this command.
cmdPrefix write channelId data - Non-writable channels do not need this command.
cmdPrefix seek channelId offset base - Non-seekable channels do not need this command. Both chan seek and chan tell use this.
cmdPrefix configure channelId option value
cmdPrefix cget channelId option - If supported, the cgetall subcommand must also be supported.
cmdPrefix cgetall channelId - If supported, the cget subcommand must also be supported.
cmdPrefix blocking channelId mode