/home/travis/build/open-telemetry/opentelemetry-python/opentelemetry-api/src/opentelemetry/context/base_context.py:docstring of opentelemetry.context.base_context.BaseRuntimeContext.register_slot:10: WARNING: py:class reference target not found: opentelemetry.context.base_context.Slot
writing additional pages...  search/home/travis/build/open-telemetry/opentelemetry-python/.tox/docs/lib/python3.7/site-packages/sphinx_rtd_theme/search.html:20: RemovedInSphinx30Warning: To modify script_files in the theme is deprecated. Please insert a <script> tag directly in your theme instead.
  {{ super() }}
done