NOTE
Functional Options Pattern
Configuring constructors through composable option functions, especially in Go APIs.
This is a historical learning note and may contain outdated or incomplete understanding.
The functional-options pattern represents optional configuration as functions applied to an object during construction. In Go, a constructor often accepts ...Option, where each option mutates or validates internal configuration.
It keeps defaults centralized and avoids constructors with many positional optional parameters. Use it for genuinely optional configuration; do not hide required dependencies or invalid states behind options.