code: def test_conversion_to_from_si():
      assert (
          convert_to(statcoulomb, coulomb, cgs_gauss)
          == coulomb / 2997924580
      )
      assert (
          convert_to(coulomb, statcoulomb, cgs_gauss)
          == 2997924580 * statcoulomb
      )
      assert (
          convert_to(
              statcoulomb,
              sqrt(gram * centimeter**3) / second,
              cgs_gauss,
          )
          == centimeter ** (S(3) / 2) * sqrt(gram) / second
      )
      assert (
          convert_to(
              coulomb, sqrt(gram * centimeter**3) / second, cgs_gauss
          )
          == 2997924580 * centimeter ** (S(3) / 2) * sqrt(gram) / second
      )
  
      # SI units have an additional base unit, no conversion in case of electromagnetism:
      assert convert_to(coulomb, statcoulomb, SI) == coulomb
      assert convert_to(statcoulomb, coulomb, SI) == statcoulomb
  
      # SI without electromagnetism:
      assert convert_to(erg, joule, SI) == joule / 10**7
      assert convert_to(erg, joule, cgs_gauss) == joule / 10**7
      assert convert_to(joule, erg, SI) == 10**7 * erg
      assert convert_to(joule, erg, cgs_gauss) == 10**7 * erg
  
      assert convert_to(dyne, newton, SI) == newton / 10**5
      assert convert_to(dyne, newton, cgs_gauss) == newton / 10**5
      assert convert_to(newton, dyne, SI) == 10**5 * dyne
      assert convert_to(newton, dyne, cgs_gauss) == 10**5 * dyne
  
file_path: sympy/sympy/physics/units/tests/test_unit_system_cgs_gauss.py
imports: from sympy.concrete.tests.test_sums_products import NS
  from sympy.core.singleton import S
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.physics.units import convert_to, coulomb_constant, elementary_charge, gravitational_constant, planck
  from sympy.physics.units.definitions.unit_definitions import angstrom, statcoulomb, coulomb, second, gram, centimeter, erg, newton, joule, dyne, speed_of_light, meter, farad, henry, statvolt, volt, ohm
  from sympy.physics.units.systems import SI
  from sympy.physics.units.systems.cgs import cgs_gauss
label_desc: Use image node_id 1 for calling a global function with example usage: test_conversion_to_from_si() without return types