Take a look at the following resources:
- Read the documentation of the regexp standard Go package, which can be found at https://golang.org/pkg/regexp/.
- Visit the main page of the grep(1) utility and find out how it supports regular expressions.
- You can find more information about the math/big Go package at https://golang.org/pkg/math/big/.
- You can find more information about YAML at https://yaml.org/.
- You might find it interesting to look at the sync.Map type explained at https://golang.org/pkg/sync/.
- Please have a look at the documentation of the unicode standard Go package at https://golang.org/pkg/unicode/.
- Although you might find it hard at first, start reading The Go Programming Language Specification at https://golang.org/ref/spec.