Protein.Atom.serial: def of bend-prot@0.1.0.0
Import: import bend-prot@0.1.0.0/protein.bend as Protein
Lines 30-34 of bend-prot@0.1.0.0/protein.bend: https://jend.leeeet.dev/read.txt?path=bend-prot@0.1.0.0/protein.bend&start_line=30&end_line=34

import Base

# Atom serial number (drops elem/pos, keeps serial)
def Atom.serial(a: Atom) -> U32:
  match a:
    case Atom{serial, elem, pos}:
      serial

Uses (2):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=bend-prot@0.1.0.0/protein.bend&name=Atom