321 flag to ignore response

[AntonZogk]

Summary

Function to help filtering values which users want to ignore when calculating the links

Checklists

This pull request meets the following requirements:

• installable with all dependencies recorded
• runs without error
• follows PEP8 and project specific conventions
• appropriate use of comments, for example no descriptive comments
• functions documented using Numpy style docstings
• assumptions and decisions log considered and updated if appropriate
• unit tests have been updated to cover essential functionality for a reasonable range of inputs and conditions
• other forms of testing such as end-to-end and user-interface testing have been considered and updated as required
• tests suite passes (locally as a minimum)
• peer reviewed with review recorded

This a low level function no need to check if it can be install at this point, no dependencies recorded it uses the pandas framework only

[robertswh]

The code is efficient and the tests are sensible. I agree the TODOs mentioned could be done in future. Happy to merge