add refseq_api.py

[alinakbase]

Description of PR purpose/changes

• Please include a summary of the change and which issue is fixed.
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• List any dependencies that are required for this change.

Testing Instructions

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Dev Checklist:

• My code follows the guidelines at https://sites.google.com/lbl.gov/trussresources/home?authuser=0
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Updating Version and Release Notes (if applicable)

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