def __init__(self, win_len: float=0.01):
    """Create a BaseVolume instance.

    :param win_len: (float) Size of the window (in seconds)
    :raises: ValueError: if win_len is not a float

    """
    self._volumes = list()
    self._rms = 0.0
    self._winlen = 0.01
    self.set_winlen(win_len)

def get_winlen(self):
    """Return the windows length used to estimate the volume values.

        :return: (float) Duration in seconds.

        """
    return self._winlen

def set_winlen(self, win_len: float):
    """Fix the windows length used to estimate the volume values.

        :param win_len: (float) Size of the window (in seconds)
        :return: (float) Assigned value for the window length.

        """
    win_len = float(win_len)
    if 0.002 <= win_len <= 0.2:
        self._winlen = win_len
    return self._winlen

def volume(self):
    """Return the global volume value (rms).

        :return: (float)

        """
    return self._rms

def volume_at(self, index: int):
    """Return the value of the volume at a given index.

        :return: (float)
        :raise: IndexError: if index is out of range

        """
    return self._volumes[index]

def volumes(self):
    """Return the list of volume values (rms).

        :return: (list of float)

        """
    return self._volumes

def len(self):
    """Return the number of RMS values that were estimated.

        :return: (int)

        """
    return len(self._volumes)

def min(self):
    """Return the minimum of RMS values.

        :return: (float) Return the min rms or 0. if no values.

        """
    if len(self._volumes) == 0:
        return 0.0
    return min(self._volumes)

def max(self):
    """Return the maximum of RMS values.

        :return: (float) Return the max rms or 0. if no values.

        """
    if len(self._volumes) == 0:
        return 0.0
    return max(self._volumes)

def mean(self):
    """Return the mean of RMS values.

        :return: (float) Return the mean rms or 0. if no values.

        """
    if len(self._volumes) == 0:
        return 0.0
    return math.fsum(self._volumes) / len(self._volumes)

def median(self):
    """Return the median of RMS values.

        :return: (float) Return the median rms or 0. if no values.

        """
    if len(self._volumes) == 0:
        return 0.0
    middle = len(self._volumes) // 2
    if len(self._volumes) % 2:
        return self._volumes[middle]
    newlist = sorted(self._volumes)
    return float(newlist[middle] + newlist[middle - 1]) / 2.0

def variance(self):
    """Return the real variance of RMS values.

        variance is 1/N * sum[(i-rms_mean)^2]

        :return: (float) Return the variance or 0. if no values.

        """
    if len(self._volumes) == 0:
        return 0.0
    rms_mean = self.mean()
    return math.fsum((pow(i - rms_mean, 2) for i in self._volumes)) / float(len(self._volumes))

def stdev(self):
    """Return the standard deviation of RMS values.

        stdev is sqrt(variance)

        :return: (float) Return the stdev or 0. if no values.

        """
    if len(self._volumes) == 0:
        return 0.0
    return math.sqrt(self.variance())

def coefvariation(self):
    """Return the coefficient of variation of RMS values.

        :return: (float) coefficient of variation given as a percentage.

        """
    m = self.mean()
    if m < 0.001:
        return 0.0
    percent_mean = m * 100.0
    return self.stdev() / percent_mean

def zscores(self):
    """Return the z-scores of RMS values.

        The z-score determines the relative location of a data value.

        :return: (list of float)

        """
    if len(self._volumes) == 0:
        return []
    all_scores = [0.0] * len(self._volumes)
    mean = self.mean()
    stdev = self.stdev()
    for i, rms_value in enumerate(self._volumes):
        all_scores[i] = (rms_value - mean) / stdev
    return all_scores

def stderr(self):
    """Calculate the standard error of the RMS values.

        :return: (float)

        """
    if len(self._volumes) == 0:
        return 0.0
    return self.stdev() / float(math.sqrt(len(self._volumes)))

def __len__(self):
    return len(self._volumes)

def __iter__(self):
    for x in self._volumes:
        yield x

def __getitem__(self, i):
    return self._volumes[i]