code: def generate_env(fname=None):
      
      config_dir = user_config_dir("genomepy")
      if os.path.exists(config_dir):
          fname = os.path.join(config_dir, "exports.txt")
          with open(fname, "w") as fout:
              for env in generate_exports():
                  fout.write("{}\n".format(env))
docs: Generate file with exports. 
  
      By default this is in .config/genomepy/exports.txt.
  
      Parameters
      ----------
      fname: strs, optional
          Name of the output file.