Function that will sum the values of two dictionaries with at least one key shared between them.

add_dict.py

def add_dicts(svs):
    """
    Performs an "add" operation on multiple SavedSearch attribute dictionaries
    to create a single attribute dictionary object by which we can perform
    filtering operations between multiple SavedSearch results.
    
    """
    
    if not svs:
        return {}
        
    # Only iterate over the keys that exist in both dictionaries
    attr_dicts = (i._attr_dict() for i in svs)
    keys = reduce(operator.or_, (set(i) for i in attr_dicts))
    results = []

    for k in keys:
        # The values of the attr dicts on SavedSearch objects are lists,
        # so we use the __add__ method on lists to combine all the values
        # for a given key across multiple dictionaries with this reduce
        # call.
        vals = reduce(operator.add, (i.get(k, []) for i in attr_dicts))
        # Before appending the results to the `results` list, filter out
        # any items in the value list that evaluate to False (e.g. empty
        # strings)
        results.append((k, filter(lambda x: x, vals)))

    # Coerce the `results` list to a dict and return.
    return dict(results)