code: def test_prefix_unit():
      m = Quantity("fake_meter", abbrev="m")
      m.set_global_relative_scale_factor(1, meter)
  
      pref = {
          "m": PREFIXES["m"],
          "c": PREFIXES["c"],
          "d": PREFIXES["d"],
      }
  
      q1 = Quantity("millifake_meter", abbrev="mm")
      q2 = Quantity("centifake_meter", abbrev="cm")
      q3 = Quantity("decifake_meter", abbrev="dm")
  
      SI.set_quantity_dimension(q1, length)
  
      SI.set_quantity_scale_factor(q1, PREFIXES["m"])
      SI.set_quantity_scale_factor(q1, PREFIXES["c"])
      SI.set_quantity_scale_factor(q1, PREFIXES["d"])
  
      res = [q1, q2, q3]
  
      prefs = prefix_unit(m, pref)
      assert set(prefs) == set(res)
      assert {v.abbrev for v in prefs} == set(symbols("mm,cm,dm"))
  
file_path: sympy/sympy/physics/units/tests/test_prefixes.py
imports: from sympy.core.mul import Mul
  from sympy.core.numbers import Rational
  from sympy.core.singleton import S
  from sympy.core.symbol import Symbol, symbols
  from sympy.physics.units import Quantity, length, meter, W
  from sympy.physics.units.prefixes import PREFIXES, Prefix, prefix_unit, kilo, kibi
  from sympy.physics.units.systems import SI
label_desc: Use image node_id 2 for calling a global function with example usage: test_prefix_unit() without return types