Slicing lets a function work with just the part of an array or slice it needs, without copying the elements. A slice expression creates a new slice header pointing into the same backing storage. Changes to shared elements are therefore visible through either slice. section 4.2.6 section 4.2
Use `a[low:high]` to select a range:
- `low` is included and `high` is excluded. For `letters := []string{"A", "B", "C", "D"}`, `letters[1:3]` contains `B` and `C`. section 4.2.6
- Omit `low` to start at zero, as in `letters[:2]`; omit `high` to continue through `len(letters)`, as in `letters[2:]`. Slicing an array likewise produces a slice backed by that array. section 4.2.6
- Use `a[low:high:max]` when the new slice should have less capacity for expansion. This limits how far an append can use the existing backing storage; it does not make shared elements independent. section 4.2.6 section 4.2
Average a measurement window
If `avg` accepts a `[]float64`, pass `avg(measurements[:10])` to average only the first ten readings, even when the collection contains more. Check `len(measurements) >= 10` first when the number of readings is uncertain: asking for an unavailable index causes a runtime panic. section 4.2.6 section 4.2.8
The same pattern keeps command-line processing focused: `for _, filename := range os.Args[1:]` visits filenames while leaving out the program name. `range` handles the resulting slice without a manual index limit. section 2.9
