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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def create_block_storage(kwargs=None, call=None):
    '''
    Create a block storage
    '''
    if call == 'action':
        raise SaltCloudSystemExit(
            'The create_block_storage function must be called with '
            '-f or --function'
        )

    conn = get_conn()

    # Assemble the composite block storage object.
    block_storage = _get_block_storage(kwargs)

    data = conn.create_block_storage(block_storage=block_storage)

    return {'BlockStorage': data}