Get the cost of a namespace.
    Returns {'amount': ..., 'units': ..., 'namespace': ...}

def get_namespace_cost( db, namespace_id ):
    """
    Get the cost of a namespace.
    Returns {'amount': ..., 'units': ..., 'namespace': ...}
    """
    lastblock = db.lastblock
    namespace_units = get_epoch_namespace_price_units(lastblock)
    namespace_fee = price_namespace( namespace_id, lastblock, namespace_units )
    
    # namespace might exist
    namespace = db.get_namespace( namespace_id )
    namespace_fee = int(math.ceil(namespace_fee))

    return {'amount': namespace_fee, 'units': namespace_units, 'namespace': namespace}