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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 sources(verbose=False):
    '''
    Return a list of available sources

    verbose : boolean (False)
        toggle verbose output

    .. versionadded:: 2019.2.0

    CLI Example:

    .. code-block:: bash

        salt '*' imgadm.sources
    '''
    ret = {}
    cmd = 'imgadm sources -j'
    res = __salt__['cmd.run_all'](cmd)
    retcode = res['retcode']
    if retcode != 0:
        ret['Error'] = _exit_status(retcode)
        return ret

    for src in salt.utils.json.loads(res['stdout']):
        ret[src['url']] = src
        del src['url']

    if not verbose:
        ret = list(ret)

    return ret