def common_base_current_gain(spec=None,i_c=0,i_e=1,beta=0):
    """
    The low frequency common-base current gain of a bipolar
    junction transistor.

    Parameters
    ----------
    spec : string, required
        Specifies calculation type. Choose 'beta' for
        calculations based on common-emitter current gain.
        The default is None.
    i_c : float, optional
        Collector current. The default is 0.
    i_e : float, optional
        Emitter current. The default is 1.
    beta : float, optional
        Common-emitter current gain. The default is 0.

    Returns
    -------
    Float value corresponding to the low freq common-base current gain

    """
    if(spec == 'beta'):
        alpha_dc = beta / (beta + 1)
    else:
        alpha_dc = i_c / i_e
    return alpha_dc