Start index parameter's name in subrange-accepting methods

[HertzDevil]

There are three different ways to name the start index parameter in a method that accepts a subrange:

• start, e.g. Array#[](start : Int, count : Int), String#byte_slice(start : Int, count : Int)
• from, e.g. Array#fill(value : T, from : Int, count : Int)
• index, e.g. Array#[]=(index : Int, count : Int, value : T), String#delete_at(index : Int, count : Int)

Across those methods, these parameters always have the same meaning and, with the exception of #fill and Slice#[], the same semantics too, so IMO they should share the same name. This would also mean one less thing to remember in case named arguments are used.

My preference is start; it captures the meaning most accurately, and is already the most frequently used name among them. from is often paired with to but the latter is absent in these overloads (if it did appear, surely from..to ought to take care of such an overload), whereas index does not indicate where the subrange is actually picked.

For comparison, all the related overloads that accept a Range seem to consistently use range as the parameter name already.