code: def test_unify_variables():
      assert list(
          unify(Basic(S(1), S(2)), Basic(S(1), x), {}, variables=(x,))
      ) == [{x: 2}]
  
imports: from sympy.core.add import Add
  from sympy.core.basic import Basic
  from sympy.core.containers import Tuple
  from sympy.core.singleton import S
  from sympy.core.symbol import Symbol, symbols
  from sympy.logic.boolalg import And
  from sympy.core.symbol import Str
  from sympy.unify.core import Compound, Variable
  from sympy.unify.usympy import deconstruct, construct, unify, is_associative, is_commutative
  from sympy.abc import x, y, z, n
label_desc: Use image node_id 5 for calling a global function with example usage: test_unify_variables() without return types