a(&block, foo)
        ^ unexpected argument after a block argument
a(&block,)
        ^ unexpected argument after a block argument
a.(&block,)
         ^ unexpected argument after a block argument
a[&block,]
        ^ unexpected argument after a block argument
def a(&block)
  p(&block,)
          ^ unexpected argument after a block argument
  a.(&block,)
           ^ unexpected argument after a block argument
  a[&block,]
          ^ unexpected argument after a block argument
end