Basic vector code, without a coordinate system class

All calculations essentially occur in the same frame.
i, j, k and x, y, z are imported as base vectors and base scalars by default on importing sympy.vector.
delop is a Del operator instance.

Example:

>>> v = 3*i - j
>>> delop ^ v
0

(delop ^ v represents curl of v)
I think the geometric module is the only other one. But I guess there arre many places in mechanics module also, where the overloaded operators are used. So I am for retaining the API. And as you pointed out, it makes the code shorter and easier to read mathematically - rather than function calls.