code: def test__unify_gens():
      assert _unify_gens([], []) == ()
  
      assert _unify_gens([x], [x]) == (x,)
      assert _unify_gens([y], [y]) == (y,)
  
      assert _unify_gens([x, y], [x]) == (x, y)
      assert _unify_gens([x], [x, y]) == (x, y)
  
      assert _unify_gens([x, y], [x, y]) == (x, y)
      assert _unify_gens([y, x], [y, x]) == (y, x)
  
      assert _unify_gens([x], [y]) == (x, y)
      assert _unify_gens([y], [x]) == (y, x)
  
      assert _unify_gens([x], [y, x]) == (y, x)
      assert _unify_gens([y, x], [x]) == (y, x)
  
      assert _unify_gens([x, y, z], [x, y, z]) == (x, y, z)
      assert _unify_gens([z, y, x], [x, y, z]) == (z, y, x)
      assert _unify_gens([x, y, z], [z, y, x]) == (x, y, z)
      assert _unify_gens([z, y, x], [z, y, x]) == (z, y, x)
  
      assert _unify_gens([x, y, z], [t, x, p, q, z]) == (
          t,
          x,
          y,
          p,
          q,
          z,
      )
  
imports: from sympy.core.mul import Mul
  from sympy.core.numbers import Integer, pi
  from sympy.core.relational import Eq
  from sympy.core.singleton import S
  from sympy.core.symbol import Symbol, 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 Integral
  from sympy.testing.pytest import raises
  from sympy.polys.polyutils import _nsort, _sort_gens, _unify_gens, _analyze_gens, _sort_factors, parallel_dict_from_expr, dict_from_expr
  from sympy.polys.polyerrors import PolynomialError
  from sympy.polys.domains import ZZ
label_desc: Use image node_id 3 for calling a global function with example usage: test__unify_gens() without return types