pub fn raster(frame: &str)Expand description
Submit a raster frame (a self-contained, pre-rendered terminal
canvas) to the channel. Producers — the plotter — call this instead of
print!-ing the frame themselves (SRD-87 §5). Routes to the installed
channel (the fd owner), falling back to a raw stdout write before any
channel is installed (bootstrap / unit tests), so behavior is unchanged.