All claims for liens and likewise all actions to recover therefor under this Act shall be assignable so as to vest in the assignee all rights and remedies herein given subject to all defenses thereto that might be raised if such assignment had not been made. Where a statement of lien has been filed as herein provided such assignment shall be made by a separate instrument in writing, which shall be recorded in the Recorder's Office where the claim was filed.
770 ILCS 70/20