We were naively creating generic typed variables whose angle brackets do
not compile and whose types are erased anyway.

Instead, if we have pure output, we can just return the method call
directly.

This functionality *is* an Op but was implemented as static utility
methods. This patch changes the implementation to be Op-based and
updated appropriately with Optional parameters.

As part of this, the HistogramCreate op has been refactored to remove
overridden implementations and simply use an Optional param.

These aren't used but they are optional and allows for addition later...

This is handled in abstract layer