add explicit paramter for infinite iterators

set appropriate value for num_epoch param for iteratos

fix long lines

remove trailing whitespace

fixed typo

remove comment

fixed comments

fixed test

to fix sequential pipeline scenario.

Add to summary output: per_pipeline_time and per_push_queue_time.
Enhance UT

Modify zip to be an inlined Op
Modify take to be an inlined Op
Modify skip to be an inlined Op
Modify rename to be an inlined Op
Modify filter to consume child's rows using one thread

change ImagefolderDV2 name

change ds.transforms.vision to ds.vision

change batch api to match map api more closely

compose op changes

test_pylint

remove compose op from vision, move to transform module, refactor map and batch to use column_order