* @throws java.io.IOException stream
*/
private void displayCompletion(String fullCompletion, String completion,
boolean appendSpace, char separator) throws IOException {
if(completion.startsWith(buffer.getLine())) {
performAction(new PrevWordAction(buffer.getCursor(), Action.DELETE));
buffer.write(completion);
terminal.writeToStdOut(completion);
//only append space if its an actual complete, not a partial
}