Adding Parity Bits

Parity bits are used as a very simple checksum to ensure that binary data isn't corrupted during transit. Here's how they work:

• If a binary string has an odd number of 1's, the parity bit is a 1.
• If a binary string has an even number of 1's, the parity bit is a 0.
• The parity bit is appended to the end of the binary string.

Create a function that adds the correct parity bit to a binary string.

Examples

addParityBit("1011011") ➞ "10110111"
// There are five 1's.
// Since five is odd, the parity bit should be a 1.
// Add the parity bit to the end of the string.
// Return the result.

addParityBit("0110000") ➞ "01100000"

addParityBit("0101101") ➞ "01011010"

addParityBit("1111111") ➞ "11111111"

Notes

All inputs will be 7-bits long (so that the parity bit makes it a full byte).