sympy/sympy — pull request #2605 by skirpichev (2013-11-17 19:43:12+00:00)
Title: Implement a new syntax for multivariable Order symbol

Supported input:
* `O(expr)`
* `O(expr, var)`
* `O(expr, var, pt)`
* `O(expr, (var1, var2, ..., varN))`
* `O(expr, (var1, var2, ..., varN), (pt1, pr2, ..., ptN))`

See also #2427.