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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 list_returners(*args):
    '''
    List the returners loaded on the minion

    .. versionadded:: 2014.7.0

    CLI Example:

    .. code-block:: bash

        salt '*' sys.list_returners

    Returner names can be specified as globs.

    .. versionadded:: 2015.5.0

    .. code-block:: bash

        salt '*' sys.list_returners 's*'

    '''
    returners_ = salt.loader.returners(__opts__, [])
    returners = set()

    if not args:
        for func in six.iterkeys(returners_):
            returners.add(func.split('.')[0])
        return sorted(returners)

    for module in args:
        if '*' in module:
            for func in fnmatch.filter(returners_, module):
                returners.add(func.split('.')[0])
        else:
            for func in returners_:
                mod_test = func.split('.')[0]
                if mod_test == module:
                    returners.add(mod_test)
    return sorted(returners)