def get_collections(db, collection=None, prefix=None, suffix=None):
    '''
    Returns a sorted list of collection names found in ``db``.
    Arguments:
        db (Database): A pymongo Database object. Can be obtained
            with ``get_db``.
        collection (str): Name of a collection. If the collection is
            present in the MongoDB database, a single-element list will
            be returned with the collecion name. If not, an empty list
            will be returned. This option is primarly included to allow
            for quick checking to see if a collection name is present.
            Default is None, which results in this option being ignored.
        prefix (str): If supplied, only collections that begin with
            ``prefix`` will be returned.
        suffix (str): If supplied, only collections that end with
            ``suffix`` will be returned.
    Returns:
        list: A sorted list of collection names.
    '''
    if collection is not None:
        return [collection, ]
    collections = db.collection_names(include_system_collections=False)
    if prefix is not None:
        collections = [c for c in collections if c.startswith(prefix)]
    if suffix is not None:
        collections = [c for c in collections if c.endswith(suffix)]
    return sorted(collections)