sympy/sympy — pull request #1254 by mrocklin (2012-04-20 18:34:00+00:00)
Title: Range set

Added a lazy range set to represent sets like 1, 2, ..., 100 .

Mimics behavior of python range.

```python

In [10]: Range(10, 60, 5)
Out[10]: {10, 15, ..., 55}

In [12]: TransformationSet(Lambda(x, sin(pi*x/60)), Range(0, 120))
Out[12]:
⎧ ⎛x⋅π⎞ ⎫
⎨sin⎜───⎟ | x ∊ {0, 1, ..., 119}⎬
⎩ ⎝ 60⎠ ⎭
```

This is currently branched off of tset_printing in PR https://github.com/sympy/sympy/pull/1251