code: def main():
      print("Hydrogen radial wavefunctions:")
      a, r = symbols("a r")
      print("R_{21}:")
      pprint(R_nl(2, 1, a, r))
      print("R_{60}:")
      pprint(R_nl(6, 0, a, r))
  
      print("Normalization:")
      i = Integral(R_nl(1, 0, 1, r) ** 2 * r**2, (r, 0, oo))
      pprint(Eq(i, i.doit()))
      i = Integral(R_nl(2, 0, 1, r) ** 2 * r**2, (r, 0, oo))
      pprint(Eq(i, i.doit()))
      i = Integral(R_nl(2, 1, 1, r) ** 2 * r**2, (r, 0, oo))
      pprint(Eq(i, i.doit()))
  
label_desc: Use image node_id 1 for calling a global function with example usage: main() without return types