How to use the crossenv.utils.overwrite_file function in crossenv

upgrade=False,
                with_pip=False)
        env.create(context.cross_env_dir)
        context.cross_bin_path = os.path.join(context.cross_env_dir, 'bin')
        context.cross_env_exe = os.path.join(
                context.cross_bin_path, context.python_exe)
        context.cross_cfg_path = os.path.join(context.cross_env_dir, 'pyvenv.cfg')
        context.cross_activate = os.path.join(context.cross_bin_path, 'activate')

        # Remove binaries. We'll run from elsewhere
        for exe in os.listdir(context.cross_bin_path):
            if not exe.startswith('activate'):
                utils.remove_path(os.path.join(context.cross_bin_path, exe))

        # Alter pyvenv.cfg
        with utils.overwrite_file(context.cross_cfg_path) as out:
            with open(context.cross_cfg_path) as inp:
                for line in inp:
                    if line.split()[0:2] == ['home', '=']:
                        line = 'home = %s\n' % self.host_project_base
                    out.write(line)

        # make a script that sets the environment variables and calls Python.
        # Don't do this in bin/activate, because it's a pain to set/unset
        # properly (and for csh, fish as well).

        # Note that env_exe hasn't actually been created yet.

        sysconfig_name = os.path.basename(self.host_sysconfigdata_file)
        sysconfig_name, _ = os.path.splitext(sysconfig_name)

        # If this venv is generated from a cross-python still in its

sysname = sys.platform[0]
            machine = platform.machine()
        else:
            sysname = host_info[0]
            machine = host_info[-1]

        config['uname'] = {
            'sysname' : sysname.title(),
            'nodename' : 'build',
            'release' : '',
            'version' : '',
            'machine' : machine,
        }

        context.crossenv_cfg = os.path.join(context.env_dir, 'crossenv.cfg')
        with utils.overwrite_file(context.crossenv_cfg) as fp:
            config.write(fp)