Step 1 :Given the piecewise-defined function \(f(x)\) as follows:
Step 2 :\[f(x)=\left\{\begin{array}{ll} 1-2 x & \text { if } x \leq -1 \\ 2 x & \text { if } -1 Step 3 :We can use this function to find \(f(x)\) for any given value of \(x\). Step 4 :However, the question does not specify which values of \(x\) we need to find \(f(x)\) for, so we cannot proceed further. Step 5 :\(\boxed{\text{The final answer is the function } f(x) \text{ itself, which can be used to find } f(x) \text{ for any given value of } x.}\)