class Opal::Nodes::Args::ExtractOptargNode


s(:fakearg) + s(:extract_post_optarg, :arg_name, …default value…)
to:
s(:optarg, :arg_name, …default value…)
In such cases InlineArgs rewriter replaces
Sometimes the argument can’t be inlined.
InlineArgs rewriter creates it to simplify compilation
This node doesn’t exist in the original AST,
^^^^^
def m(a = 1); end
Compiles extraction of a single inline optional argument

def compile 

def compile
  return if default_value.children[1] == :undefined
  push "if (#{name} == null) #{name} = ", expr(default_value)
end