These print statements were not warnings, they're simply
printing things out that work as designed. This is never a
good design - it should not emit anything but warnings.

I considered adding a `quiet` keyword, but that doesn't seem
warranted here.

[ci skip]

* replace superfluous single-character regex character
classes with their literal string equivalents; this
avoids the overhead associated with a character class
when there's only a single character enclosed (so there's
no benefit to the class overhead)

* for more information see:
Chapter 6 of:
Friedl, Jeffrey. Mastering Regular Expressions. 3rd ed.,
O’Reilly Media, 2009.

Signed-off-by: Changqing Li <changqing.li@windriver.com>

As numpy is Python 3 only, these import statements are now unnecessary
and don't alter runtime behavior.