how to declare entity reference in dynamics crm Azure function code

Hi Guys,

AnyBody know how to declare entity reference in dynamics crm azure function coding. Here i write line for declare entity reference but itshowing error. My code is

       var accountType = ((EntityReference)appl.Attributes["new_requestedroleid"]).LogicalName;

But it Showing System.colletion.generics exception error occur in that line..i don't know why it is happening..can u please tell me how to declare entity reference and get the name filed value from the lookup field record.