According to the docs, we are able to create a Symmetric matrix from another matrix that is already stored in memory:

```
A = eye(3)
B = Symmetric(A)
sizeof(A) # 72 bytes
sizeof(B) # 16 bytes
```

How to populate a Symmetric matrix directly without having to store a full matrix? In particular, if we could index a Symmetric matrix and have the expected behavior that whenever `B[i,j]`

is set to `b`

, `B[j,i]`

is automatically set to `b`

, that would be very useful.

I would like to save memory while working with big covariance matrices and also be able to enforce symmetry in the type to dispatch the appropriate LinAlg solvers. Is this a feature that you consider relevant?

```
B[1,1] # ERROR: not supported
```