         case .SymbolEl("="): return evalTwo(rest, eq)
         case .SymbolEl("<"): return evalTwo(rest, <)
         case .SymbolEl("<="): return evalTwo(rest, <=)
-        case .SymbolEl("define"): return storeInEnv(rest, env)
         default: return .NilEl
         }
     }

            return evalProgn(restUneval, env)
        } else if f == .SymbolEl("let") {
            return evalLet(restUneval, env)
        }
        
        // post eval functions


public func storeInEnv(elements: ArraySlice<Element>, env: Env) -> Element {
    if elements.count == 2 {
        env.store(elements[0], value: eval(elements[1], env))
        return elements[1]
    } else {
        return .NilEl
