method
downcase
![Some documentation Importance_1](https://d2vfyqvduarcvs.cloudfront.net/images/importance_1.png?1349367920)
downcase()
public
Returns a copy of str with all uppercase letters replaced with their lowercase counterparts. The operation is locale insensitive—only characters “A” to “Z” are affected. Note: case replacement is effective only in ASCII region.
"hEllO".downcase #=> "hello"