If I have a turing machime TM, can I recognize end of input on the tape?
I know that the "end of input" in a turing machine is signaled with a special character, $\sqcup$.
Can I do this -
Let $TM$ be a turing machine.
Until we reach the first $\sqcup$, continue. If we reached $\sqcup$, replace it with a special character - #.
Is it "legal" to that this?