Add Order.variables to the return value of Order.free_symbols
Draft: Order for point's != 0 or oo
Some tests for point != 0 and oo
alter subs for Order (XXX)
fix docstring of Order class
right series() for x0!=0
fix expr.series() docstring
fix gamma series for x0=-1
dirty workaround in Order.new to prevent O((x-1)**2,x,1).simplify() -> O(1,x,1)
Fix O for point != 0 and oo
Fix series for x0!=0
More fixes for subs
In _eval_subs - fallback to the old method if new expr has multiple symbols
Fix example with series for x0!=0 in the tutorial
An example of series for x0!=0