code: def test_empty_rust_code():
      code_gen = RustCodeGen()
      output = StringIO()
      code_gen.dump_rs([], output, "file", header=False, empty=False)
      source = output.getvalue()
      assert source == ""
  
imports: from io import StringIO
  from sympy.core import S, symbols, pi, Catalan, EulerGamma, Function
  from sympy.core.relational import Equality
  from sympy.functions.elementary.piecewise import Piecewise
  from sympy.utilities.codegen import RustCodeGen, codegen, make_routine
  from sympy.testing.pytest import XFAIL
  import sympy
label_desc: Use image node_id 1 for calling a global function with example usage: test_empty_rust_code() without return types