code: def test_extend():
      ms = DimensionSystem((length, time), (velocity,))
  
      mks = ms.extend((mass,), (action,))
  
      res = DimensionSystem((length, time, mass), (velocity, action))
      assert mks.base_dims == res.base_dims
      assert mks.derived_dims == res.derived_dims
  
file_path: sympy/sympy/physics/units/tests/test_dimensionsystem.py
imports: from sympy.core.symbol import symbols
  from sympy.matrices.dense import Matrix, eye
  from sympy.physics.units.definitions.dimension_definitions import action, current, length, mass, time, velocity
  from sympy.physics.units.dimensions import DimensionSystem
label_desc: Use image node_id 1 for calling a global function with example usage: test_extend() without return types