code: def test_global_vars_rust():
      x, y, z, t = symbols("x y z t")
      result = codegen(
          ("f", x * y),
          "Rust",
          header=False,
          empty=False,
          global_vars=(y,),
      )
      source = result[0][1]
      expected = (
          "fn f(x: f64) -> f64 {\n"
          "    let out1 = x*y;\n"
          "    out1\n"
          "}\n"
      )
      assert source == expected
  
      result = codegen(
          ("f", x * y + z),
          "Rust",
          header=False,
          empty=False,
          argument_sequence=(x, y),
          global_vars=(z, t),
      )
      source = result[0][1]
      expected = (
          "fn f(x: f64, y: f64) -> f64 {\n"
          "    let out1 = x*y + z;\n"
          "    out1\n"
          "}\n"
      )
      assert source == expected
  
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 21 for calling a global function with example usage: test_global_vars_rust() without return types