\message{an example of two dimensional graph in plainTeX by Adam Purkrt 2020}\def\xy#1#2{\kern#1pt\raise#2pt\hbox to 0pt{\vrule width 4pt height 4pt\hss}\kern-#1pt}\leavevmode\xy{40}{40}\xy{10}{10}\xy{50}{50}\xy{30}{30}\xy{0}{0}\xy{20}{20}\xy{100}{100}\xy{70}{70}\xy{60}{60}\xy{90}{90}\xy{80}{80}\hbox to 0pt{\vrule height 104pt width 1pt\hss}\hbox to 0pt{\vrule width 104pt height 1pt\hss}\bye
