Add more custom formulas like =GPT_EXTRACT, =GPT_FORMAT, GPT_SUMMARIZE

For example

using

=GPT_FORMAT("14 February 71", "iso")

would return 14/02/1971

or

=GPT_EXTRACT("I worked 5 years at Amazon.com and then 3 years at Apple", "companies")

would return Amazon, Apple

GPT_SUMMARIZE would just summarize the cell applied to