* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* back fl

* delete ssl cert

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* make warning

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* unittest paral degree

* solve unittest

* heter & multi cloud commm ready

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* fl-ps v1.0

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* support N + N mode

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* delete print

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