def compute_chunk(source, target, chunk, chunk_expr, parts):
 (source_part, target_part) = parts
 part = source[source_part]
 result = compute(chunk_expr, {chunk: part}, return_type='native')
 target[target_part] = result

def compute_chunk ( source , target , chunk , chunk_expr , parts ) : ( source_part , target_part ) = parts part = source [ source_part ] result = compute ( chunk_expr , { chunk : part } , return_type = 'native' ) target [ target_part ] = result
pull out a part .