class RuboCop::Cop::Style::StringMethods

from the String class.
This cop enforces the use of consistent method names

def autocorrect(node) 

def autocorrect(node)
  lambda do |corrector|
    corrector.replace(node.loc.selector,
                      preferred_method(node.method_name))
  end
end

def message(node) 

def message(node)
  format(MSG, preferred_method(node.method_name), node.method_name)
end

def on_send(node) 

def on_send(node)
  return unless preferred_method(node.method_name)
  add_offense(node, :selector)
end