code: def test_norm():
      # Maximum "n" which is tested:
      n_max = 2  # it works, but is slow, for n_max > 2
      for n in range(n_max + 1):
          for l in range(n):
              assert (
                  integrate(R_nl(n, l, r) ** 2 * r**2, (r, 0, oo))
                  == 1
              )
  
file_path: sympy/sympy/physics/tests/test_hydrogen.py
imports: from sympy.core.numbers import I, Rational, oo, pi
  from sympy.core.singleton import S
  from sympy.core.symbol import symbols
  from sympy.functions.elementary.exponential import exp
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.trigonometric import cos, sin
  from sympy.integrals.integrals import integrate
  from sympy.simplify.simplify import simplify
  from sympy.physics.hydrogen import R_nl, E_nl, E_nl_dirac, Psi_nlm
  from sympy.testing.pytest import raises
label_desc: Use image node_id 3 for calling a global function with example usage: test_norm() without return types