def METHOD_NAME(x, F=30, n_mask=2, replace_with_zero=True, inplace=False):
    """freq mask for spec agument
    :param numpy.ndarray x: (time, freq)
    :param int n_mask: the number of masks
    :param bool inplace: overwrite
    :param bool replace_with_zero: pad zero on mask if true else use mean
    """
    if inplace:
        cloned = x
    else:
        cloned = x.copy()
    num_mel_channels = cloned.shape[1]
    fs = numpy.random.randint(0, F, size=(n_mask, 2))
    for f, mask_end in fs:
        f_zero = random.randrange(0, num_mel_channels - f)
        mask_end += f_zero
        # avoids randrange error if values are equal and range is empty
        if f_zero == f_zero + f:
            continue
        if replace_with_zero:
            cloned[:, f_zero:mask_end] = 0
        else:
            cloned[:, f_zero:mask_end] = cloned.mean()
    return cloned