<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def v1_stream_id_associations(tags, stream_id):
    '''Retrieve associations for a given stream_id.

    The associations returned have the exact same structure as defined
    in the ``v1_tag_associate`` route with one addition: a ``tag``
    field contains the full tag name for the association.
    '''
    stream_id = stream_id.decode('utf-8').strip()
    return {'associations': tags.assocs_by_stream_id(stream_id)}