Lua, 54 bytes

The one time the Lua submission is actually short!

…so yeah, it's another "just overload the operator" situation. Props to h for being a free nil value, since Lua considers almost everything truthy.

a={}b=0setmetatable(a,{__band=function()return h end}) 

Try it online!

Lua, 54 43 bytes

The one time the Lua submission is actually short!

…so yeah, it's another "just overload the operator" situation.

-11 bytes by Adamátor

a=setmetatable({},{__band=loadstring""})b=0 

• current version
• original version