_ = 1 as Str # ERR
_ = 1 as Never # ERR

n = 1
_ = n.times!
i = n as Int
_ = i.times! # ERR

v: Array!(Int or Str, 2) = ![1, 2]
v.push! 1 # OK
v.push! "a" # ERR
v.push! None # ERR

v2 as Array!(Int or Str, 2) = ![1, 2]
v2.push! 1 # OK
v2.push! "a" # OK
v2.push! None # ERR

v3 = v2 as Array!(Int or Str or NoneType, _)
v3.push! None # OK