What is the role of the "prime" marker on this expression? This expression appears on my cryptography homework: $$G'(k) = G(k \oplus 1^s)$$ It is a description of a Pseudorandom Number Generator where $G:\\{0,1\\}^s \to \\{0,1\\}^n$ I just cant see what the "prime" adds, to me it would read the same as: $$G(k) = k \oplus 1^s$$ Am I missing something?

Given one generator $G \colon \\{0,1\\}^s \to \\{0,1\\}^n$ we define another generator as follows: Given $k$, first swap all bits, that is xor with $1^s$, then apply $G$, as a formula: We define $G'\colon \\{0,1\\}^s \to \\{0,1\\}^n$ by $G'(k) = G(k \oplus 1^s)$.

For example: $G'(100) = G(001)$, $G'(111) = G(000)$ and so on.