code: def get_string(dump_fn, routines, prefix="file", **kwargs):
      """Wrapper for dump_fn. dump_fn writes its results to a stream object and
      this wrapper returns the contents of that stream as a string. This
      auxiliary function is used by many tests below.
  
      The header and the empty lines are not generator to facilitate the
      testing of the output.
      """
      output = StringIO()
      dump_fn(routines, output, prefix, **kwargs)
      source = output.getvalue()
      output.close()
      return source
  
imports: import os
  import tempfile
  import shutil
  from io import StringIO
  from sympy.core import symbols, Eq
  from sympy.utilities.autowrap import autowrap, binary_function, CythonCodeWrapper, UfuncifyCodeWrapper, CodeWrapper
  from sympy.utilities.codegen import CCodeGen, C99CodeGen, CodeGenArgumentListError, make_routine
  from sympy.testing.pytest import raises
  from sympy.testing.tmpfiles import TmpFileManager
label_desc: Use image node_id 1 for calling a global function with example usage: get_string(dump_fn, routines, prefix) and returns: source