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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_target_list(module, action_parameter=None):
    '''
    List available targets for the given module.

    module
        name of the module to be queried for its targets

    action_parameter
        additional params passed to the defined action

        .. versionadded:: 2016.11.0

    CLI Example:

    .. code-block:: bash

        salt '*' eselect.get_target_list kernel
    '''
    exec_output = exec_action(module, 'list', action_parameter=action_parameter)
    if not exec_output:
        return None

    target_list = []
    if isinstance(exec_output, list):
        for item in exec_output:
            target_list.append(item.split(None, 1)[0])
        return target_list

    return None