Stringlist field in if statement

Stringlist field in if statement

OK so I'm sure this is simple but I keep getting a syntax error saying 

Encountered ")" at line 1, column 37.
Was expecting one of:
"," ...
"*" ...
"/" ...
"%" ...






In the field action for Device_Thrombus on user input I am trying to hide all the fields on the form if they select No. Device_Thrombus is a checkbox field with the values Yes and No.
if (input.Device_Thrombus.size() > 0)
{
 if(input.Device_Thrombus.contains("No"))
{
hide input.If_YES_Covers_threaded_insert;
hide input.Thrombus_Covers_Threaded_Insert;
hide input.Thrombus_Mobility;
}
}