[From string (line 18) ]                                                               
                                                                                       
@startuml                                                                              
!unquoted function $lookup($id)                                                        
                                                                                       
'!$data = %loadJSON("system.json")                                                     
!$data={"participants" :[                                                              
{"id": "cm" ,"label": "customer master","desc": "manages customers"},                  
{"id": "tm" ,"label": "transaction manager","desc": "manages transactions"},           
{"id": "am" ,"label": "account master","desc": "manages accounts"}                     
]                                                                                      
}                                                                                      
                                                                                       
!foreach $part in $data.participants                                                   
  !if $part.id == $id                                                                  
    :id=$part.id \nlabel=$part.label \ndesc=$part.desc;                                
  !endif                                                                               
!endfor                                                                                
                                                                                       
!endfunction                                                                           
^^^^^                                                                                  
 This function does not have any !return directive. Declare it as a procedure instead ?