code: def test_dim():
      dimsys = UnitSystem((m, kg, s), (c,))
      assert dimsys.dim == 3
  
file_path: sympy/sympy/physics/units/tests/test_unitsystem.py
imports: from sympy.physics.units import DimensionSystem, joule, second, ampere
  from sympy.core.numbers import Rational
  from sympy.core.singleton import S
  from sympy.physics.units.definitions import c, kg, m, s
  from sympy.physics.units.definitions.dimension_definitions import length, time
  from sympy.physics.units.quantities import Quantity
  from sympy.physics.units.unitsystem import UnitSystem
  from sympy.physics.units.util import convert_to
label_desc: Use image node_id 5 for calling a global function with example usage: test_dim() without return types