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)
This is just on the lines of what's done in sympy.physics.vector currently. The whole idea is that a user _generally_ would not need to initialize a BaseVector. Once coordinate systems are implemented/come into the picture, a system would initialize its own vectors as 'C.i, C.j, C.k' etc by default -otherwise, a user would specify the names he requires. So what you suggest would be done in that class. Currently, 'i', 'j' and 'k' are initialized similarly by default.