human
Complete the below
def AumSortedConcatenate():

    ''''String concatenation aggregator for the author sort map'
    '''
assistant
#Here is the Python code you requested.
    def step(ctxt, ndx, author, sort, link):
        if (author is not None):
            ctxt[ndx] = u':::'.join((author, sort, link))
    def finalize(ctxt):
        keys = list(ctxt.iterkeys())
        l = len(keys)
        if (l == 0):
            return None
        if (l == 1):
            return ctxt[keys[0]]
        return u':#:'.join([ctxt[v] for v in sorted(keys)])
    return ({}, step, finalize)