How do I make a condition with an element set.

[crusader]

I am trying to link a command with elements sets rather then weapon ids.
I put:

def self.w_range(id)
    case id
    when 1; range = [4, 0, true, false, 0]
    else; range = [1, 0, false, false, 0]
    end
   
   
    if self.element_set.include?(9)
     range = [6, 0, true, false, 0]
     end
   
    return range
 
    end

It tells me it is not a recognized method.