# Associate a `npropdef` with its `mpropdef`
	#
	# Be careful, this method is unsafe, no checking is done when it's used.
	# The safe way to add method it's to use the `build_property`
	#
	# See `mpropdef2npropdef`
	fun unsafe_add_mpropdef2npropdef(mpropdef: MPropDef,npropdef: APropdef)
	do
		mpropdef2npropdef[mpropdef] = npropdef
	end