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Compile Function Add(Num1, Num2)


    // The usual way of defaulting parameters, which will still break if Num1 is ""
    If Unassigned(Num1) then Num1 = 0
    If Unassigned(Num2) then Num2 = 0


    // To be even safer, we need to check for both "" and unassigned... but this will break too
    // because BASIC+ evaluates all expressions in an condition, even if the first expression
    // makes the condition true. Thus, these statements will break to the debugger if Num1 or Num2
    // is unassigned.
    If Unassigned(Num1) OR Num1 EQ "" then Num1 = 0
    If Unassigned(Num2) OR Num2 EQ "" then Num2 = 0


	// This is even safer, but the arithmetic will break to the debugger if Num1 or Num2 contains
    // non-digits or is too big to be a number.
    If Unassigned(Num1) then
        Num1 = 0
    end else
        If Num1 EQ "" then Num1 = 0
    end
    If Unassigned(Num2) then
        Num2 = 0
    end else
        If Num2 EQ "" then Num2 = 0
    end


    // SRP_Num covers all the bases
    Num1 = SRP_Num(Num1, 0)
    Num2 = SRP_Num(Num2, 0)

Return Num1 + Num2