font-FiraCode/features/calt/numbersigns.fea

lookup numbersigns {
  # middle parts
  sub [numbersign_start.seq numbersign_middle.seq] numbersign' numbersign by numbersign_middle.seq;

  # ends
  sub [numbersign_start.seq numbersign_middle.seq] numbersign' by numbersign_end.seq;
  
  # beginnings
  sub numbersign' numbersign by numbersign_start.seq; 
} numbersigns;