# Set the default `self` value
	#
	# `expr`: Represents the default value of the attribute. If `expr isa ABlockExpr` `self.n_block` will be set.
	fun define_default(expr: AExpr): AAttrPropdef
	do
		self.has_value = true
		if expr isa ABlockExpr then
			self.n_block = expr
		else
			self.n_expr = expr
		end
		return self
	end