Find the Exact Value of the Expression $$\tan ^ { - 1 } \left[ \tan \left( - \frac { \pi } { 8 } \right) \right]$$

Multiple Choice

Find the exact value of the expression. Do not use a calculator.
- $$\tan ^ { - 1 } \left[ \tan \left( - \frac { \pi } { 8 } \right) \right]$$

A) $- 8 \pi$
B) $\frac { \pi } { 8 }$
C) $8 \pi$
D) $- \frac { \pi } { 8 }$