docstr: Returns a cmd
code: def get_cmd(self, metadata=None):
      """Returns a cmd"""
      if metadata is None:
          metadata = {
              "name": "fake",
              "version": "1.0",
              "url": "xxx",
              "author": "xxx",
              "author_email": "xxx",
          }
      dist = Distribution(metadata)
      dist.script_name = "setup.py"
      dist.packages = ["somecode"]
      dist.include_package_data = True
      cmd = sdist(dist)
      cmd.dist_dir = "dist"
      return dist, cmd
  
imports: import os
  import tarfile
  import unittest
  import warnings
  import zipfile
  from os.path import join
  from textwrap import dedent
  from test.test_support import captured_stdout, check_warnings, run_unittest
  from distutils.command.sdist import sdist, show_formats
  from distutils.core import Distribution
  from distutils.tests.test_config import PyPIRCCommandTestCase
  from distutils.errors import DistutilsOptionError
  from distutils.spawn import find_executable
  from distutils.log import WARN
  from distutils.filelist import FileList
  from distutils.archive_util import ARCHIVE_FORMATS
label_desc: Use image node_id 3 for calling the SDistTestCase obj's underlying member method code with example usage: obj.get_cmd(metadata) and returns: dist,  cmd