Binomial coeff are not expanded by default
Made some fixes, updated some tests
Fixed doctest. Added tests, documentation and doctest
Rewrote docstring
Merge branch 'master' of https://github.com/sympy/sympy into binomial-iss3544
Changed the test to check for func
Fixed issue 3538. Subs working in .n()
Added test
In use2to3, only use WindowsError in Windows

Fixes issue 3457.
tweak trigsimp

- make sure c is in match result
- break loop if expression is unchanged
add rebuild rule
add yieldify branching strategy
add yieldify imports
Rewrite rule takes condition
docstring for rewriterule
rewriterule supports new assumptions
fix rewriterule doctest
evalf_trig handles complex arguments without raising exceptions
Merge branch 'master' of https://github.com/sympy/sympy into evalf-trig-iss3538
Merge pull request #1726 from prasoon2211/binomial-iss3544

Binomial coefficients are not expanded by default