# Return an `AIfExpr` with the contract encapsulated by an `if` to check if it's already in a contract verification.
	#
	# Example:
	# ~~~nitish
	# class A
	# 	fun bar([...]) is except([...])
	#
	# 	fun _contract_bar([...])
	#	do
	#		if not sys._in_contract_ then
	#			sys._in_contract_ = true
	#			_bar_expect([...])
	#			sys._in_contract_ = false
	#		end
	#		bar([...])
	#	end
	#
	# 	fun _bar_expect([...])
	# end
	# ~~~~
	#
	private fun encapsulated_contract_call(visited_method: AMethPropdef, call_to_contracts: Array[ACallExpr]): AIfExpr
	do
		var sys_property = toolcontext.modelbuilder.model.get_mproperties_by_name("sys").first.as(MMethod)
		var callsite_sys = ast_builder.create_callsite(toolcontext.modelbuilder, visited_method, sys_property, true)

		var incontract_attribute = get_incontract

		var callsite_get_incontract = ast_builder.create_callsite(toolcontext.modelbuilder, visited_method, incontract_attribute.getter.as(MMethod), false)
		var callsite_set_incontract = ast_builder.create_callsite(toolcontext.modelbuilder, visited_method, incontract_attribute.setter.as(MMethod), false)

		var n_condition = ast_builder.make_not(ast_builder.make_call(ast_builder.make_call(new ASelfExpr, callsite_sys, null), callsite_get_incontract, null))

		var n_if = ast_builder.make_if(n_condition, null)

		var if_then_block = n_if.n_then.as(ABlockExpr)

		if_then_block.add(ast_builder.make_call(ast_builder.make_call(new ASelfExpr, callsite_sys, null), callsite_set_incontract, [new ATrueExpr.make(mainmodule.bool_type)]))
		if_then_block.add_all(call_to_contracts)
		if_then_block.add(ast_builder.make_call(ast_builder.make_call(new ASelfExpr, callsite_sys, null), callsite_set_incontract, [new AFalseExpr.make(mainmodule.bool_type)]))

		return n_if
	end