def euclidean(v1, v2, c=False):
    """
    Find the euclidean distance between two vectors
    or between a vector and a collection of vectors.

    Parameters
    ----------
    v1 : list, first 3D vector or collection of vectors
    v2 : list, second 3D vector
    c : bool (default=False), if True, it means the v1 is a list of vectors.

    Returns
    -------
    list of list of euclidean distances if c==True.
    Otherwise float: the euclidean distance
    """
    if c:
        res = []
        for _v in v1:
            res.append([np.sqrt((_v[0] - v2[0]) ** 2 +
                                (_v[1] - v2[1]) ** 2 +
                                (_v[2] - v2[2]) ** 2)])
        return np.asarray(res)
    return np.sqrt((v1[0] - v2[0]) ** 2 +
                   (v1[1] - v2[1]) ** 2 +
                   (v1[2] - v2[2]) ** 2)

    Find the euclidean distance between two vectors
    or between a vector and a collection of vectors.

    Parameters
    ----------
    v1 : list, first 3D vector or collection of vectors
    v2 : list, second 3D vector
    c : bool (default=False), if True, it means the v1 is a list of vectors.

    Returns
    -------
    list of list of euclidean distances if c==True.
    Otherwise float: the euclidean distance
    
pyod/models/rod.py