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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_project_id():
 """Gets the project ID from the Cloud SDK. Returns: Optional[str]: The project ID. """

    if os.name == 'nt':
        command = _CLOUD_SDK_WINDOWS_COMMAND
    else:
        command = _CLOUD_SDK_POSIX_COMMAND

    try:
        output = subprocess.check_output(
            (command,) + _CLOUD_SDK_CONFIG_COMMAND,
            stderr=subprocess.STDOUT)
    except (subprocess.CalledProcessError, OSError, IOError):
        return None

    try:
        configuration = json.loads(output.decode('utf-8'))
    except ValueError:
        return None

    try:
        return configuration['configuration']['properties']['core']['project']
    except KeyError:
        return None