def get_identical_attributes(features, exclude=None):
    """Return a dictionary of all key-value pairs that are identical for all |SegmentChains| in `features`
    
    Parameters
    ----------
    features : list 
        list of |SegmentChains|

    exclude : set
        attributes to exclude from identity criteria
    
    Returns
    -------
    dict
        Dictionary of all key-value pairs that have identical values in all the
        `attr` dictionaries of all the features in `features`
    """
    exclude = [] if exclude is None else exclude
    common_keys = set(features[0].attr.keys())
    for feature in features:
        common_keys &= set(feature.attr.keys())

    common_keys -= set(exclude)

    dtmp = { K : features[0].attr[K] for K in common_keys \
                 if all([X.attr[K] == features[0].attr[K] for X in features]) == True }
    return dtmp