**Input:** 
  A bit vector of length 3 represented as a `Bool[]` - a binary representation of a number in little endian notation.

**Output:**
  Return `true` if the input array represents the number $7$, and `false` otherwise.

**Examples:**

* If the input array is `[true, true, true]`, return `true`.
* If the input array is `[true, true, false]`, return `false`.
