Vitali Kurdasov 
Has successfully completed the online course Intermediate (200)
Has successfully completed the online course Basics (100)
Has successfully completed the online course Advanced (310)
Has successfully completed the Intermediate CertificationHello Leonid,
in order to use a output of a already called BO as an input for another BO you could use the “process output”-shape in the input mapping of the second BO. 
Also, if the input is not optional and it has to be set, than please use the switch in the input parameter section of the second BO and set “optional” to false.
