Identity
From specialfunctionswiki
Let $X$ be any set. The function $\mathrm{id} \colon X \rightarrow X$ defined by $\mathrm{id}(x)=x$ is called the identity function on $X$.
Domain coloring of $\mathrm{id}$.
Let $X$ be any set. The function $\mathrm{id} \colon X \rightarrow X$ defined by $\mathrm{id}(x)=x$ is called the identity function on $X$.
Domain coloring of $\mathrm{id}$.