# Return all prefixes currently declared for an URI.
	#
	# This method returns prefixes mapped to a specific Namespace
	# URI. The `xml` prefix will be included. If you want only one
	# prefix that's mapped to the Namespace URI, and you don't care
	# which one you get, use the `prefix` method instead.
	#
	# Note: the empty (default) prefix is *never* included
	# in this enumeration; to check for the presence of a default
	# Namespace, use the `uri` method with an argument of `""`.
	#
	# Parameters:
	#
	# * `uri`: The Namespace URI.
	#
	# SEE: `prefix`
	#
	# SEE: `declared_prefixes`
	#
	# SEE: `uri`
	fun prefixes_of(uri: String): Collection[String] do
		var prefixes = new Array[String]
		var all_prefixes = self.prefixes

		for prefix in all_prefixes do
			if uri == self.uri(prefix) then
				prefixes.push(prefix)
			end
		end
		return prefixes
	end