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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 valid():
    '''
    List valid entries in mine configuration.

    CLI Example:

    .. code-block:: bash

        salt '*' mine.valid
    '''
    m_data = __salt__['config.merge']('mine_functions', {})
    # If we don't have any mine functions configured, then we should just bail out
    if not m_data:
        return

    data = {}
    for func in m_data:
        if m_data[func] and isinstance(m_data[func], dict):
            mine_func = m_data[func].pop('mine_function', func)
            if not _mine_function_available(mine_func):
                continue
            data[func] = {mine_func: m_data[func]}
        elif m_data[func] and isinstance(m_data[func], list):
            mine_func = func
            if isinstance(m_data[func][0], dict) and 'mine_function' in m_data[func][0]:
                mine_func = m_data[func][0]['mine_function']
                m_data[func].pop(0)

            if not _mine_function_available(mine_func):
                continue
            data[func] = {mine_func: m_data[func]}
        else:
            if not _mine_function_available(func):
                continue
            data[func] = m_data[func]

    return data