Interpret Absolute Value Functions as Piecewise

What absolute value function does the following piecewise function represent? $$f(x) = \begin{cases} \begin{align} 4x+1 \quad \text{ if }& \quad 4x+1 \geq 0\\ -4x-1 \quad \text{ if }& \quad 4x+1 < 0\\ \end{align} \end{cases}$$