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
Merge pull request #1726 from prasoon2211/binomial-iss3544

Binomial coefficients are not expanded by default