Fixes Issue 152

[duggalsu]

Description

• Removed __len__ from SpanPointer and DocPointer
• Removed assert statements on len for SpanPointer and DocPointer from tests

How has this been tested?

• Ran all tests successfully

Checklist

• [x] I have followed the Contribution Guidelines and Code of Conduct
• [x] I have commented my code following the OpenMined Styleguide
• [ ] I have labeled this PR with the relevant Type labels
• [x] My changes are covered by tests

[duggalsu]

Hi @Nilanshrajput , does this look ok ?

[Nilanshrajput]

LGTM !!

[Nilanshrajput]

Thanks for your contribution @duggalsu !!!