For AI agents: visit https://lucid.readme.io/llms.txt for an index of all pages formatted in Markdown and endpoints in OpenAPI. Append .md to any documentation page URL to get its markdown version.
return the percentage of a that overlaps with b.
if a is entirely within b, it returns 1 (or a number a little less than 1
(e.g., 0.99999999999) due to numerical inaccuracy); if a is entirely
outside b, it returns 0.
