--- !ruby/object:RI::MethodDescription 
aliases: []

block_params: 
comment: 
- !ruby/struct:SM::Flow::P 
  body: Downcases the contents of <em>str</em>, returning <tt>nil</tt> if no changes were made.
full_name: String#downcase!
is_singleton: false
name: downcase!
params: |
  str.downcase!   => str or nil

visibility: public
