## Test Bit

Given a number, write a function that tests if its i^{th} bit is set.

We'll say that the bits are numbered from the least significant bit (on the right) to the most significant bit (on the left).

So, the binary
number 0000 0001 has
the 0^{th} bit set and all the rest
of its bits are *clear* (not set).

## Single Bit Set

Given a number, write a function that determines if the number has exactly one bit set.

Sometimes, you'll hear this problem framed in terms of powers of two: "Write a function that determines if a number is a power of two."

All powers of two have exactly one bit set, so these questions are identical.