class Build::Environment

def checksum_recursively(digester)

def checksum_recursively(digester)
	sorted_keys.each do |key|
		digester.update(key.to_s)
		
		case value = @values[key]
		when Proc
			digester.update(value.source_location.join)
		else
			digester.update(value.to_s)
		end
	end
	
	@parent.checksum_recursively(digester) if @parent
end