Function default_config 

pub fn default_config() -> Config

Reasonable default Config.

• bottom_x / left_y: axis line, ticks, labels, and title all on. Text is empty — fill in via Chart::with_x_title / with_y_title.
• top_x / right_y: axis line and inside ticks on (kept for the frame); labels and axis title off. Enable those for special charts (e.g. dual-axis).
• chart_title: title band reserved; text empty until Chart::with_title.