class Rubocop::Cop::Style::NilComparison

if !x.nil?
if x.nil?
# good
if x != nil
if x == nil
# bad
@example
This cop checks for comparison of something with nil using ==.

def on_send(node) 

def on_send(node)
  # lambda.() does not have a selector
  return unless node.loc.selector
  op = node.loc.selector.source
  if OPS.include?(op)
    _receiver, _method, args = *node
    convention(node, :selector) if args == NIL_NODE
  end
end