这个代码示例中的逗号是什么?

cash = 100_000.00
sum = 0
cash += 1.00, sum while cash < 1_000_000.00 # underscores ignored

syntax error, unexpected ',', expecting $end

#Also, like if, you can use while as a statement modifier, at the end of a statement:
cash = 100_000.00
sum = 0
cash += 1.00, sum while cash < 1_000_000.00 # underscores ignored
#So cash just keeps adding up until it equals $1,000,000.00. I like that!