# Capitalizes each word in `self`
	#
	# Letters that follow a letter are lowercased
	# Letters that follow a non-letter are upcased.
	#
	# If `keep_upper = true`, uppercase letters are not lowercased.
	#
	# When `src` is specified, this method reads from `src` instead of `self`
	# but it still writes the result to the beginning of `self`.
	# This requires `self` to have the capacity to receive all of the
	# capitalized content of `src`.
	#
	# SEE: `Char::is_letter` for the definition of a letter.
	#
	# ~~~
	# var b = new FlatBuffer.from("jAVAsCriPt")
	# b.capitalize
	# assert b == "Javascript"
	# b = new FlatBuffer.from("i am root")
	# b.capitalize
	# assert b == "I Am Root"
	# b = new FlatBuffer.from("ab_c -ab0c ab\nc")
	# b.capitalize
	# assert b == "Ab_C -Ab0C Ab\nC"
	#
	# b = new FlatBuffer.from("12345")
	# b.capitalize(src="foo")
	# assert b == "Foo45"
	#
	# b = new FlatBuffer.from("preserve my ACRONYMS")
	# b.capitalize(keep_upper=true)
	# assert b == "Preserve My ACRONYMS"
	# ~~~
	fun capitalize(keep_upper: nullable Bool, src: nullable Text) do
		src = src or else self
		var length = src.length
		if length == 0 then return
		keep_upper = keep_upper or else false

		var c = src[0].to_upper
		self[0] = c
		var prev = c
		for i in [1 .. length[ do
			prev = c
			c = src[i]
			if prev.is_letter then
				if keep_upper then
					self[i] = c
				else
					self[i] = c.to_lower
				end
			else
				self[i] = c.to_upper
			end
		end
	end