I tried
ENV.clear

But it doesn't work, with the error message:
../env.rb:56: undefined method `clear' for #<Object:0x401d0d28> (NameError)

I thought ENV is a Hash, so clear is defined. However, when I tried:
puts ENV.type

it turns out ENV is only an Object.


However, the Hash function delete(key) is defined for ENV. That is very strange.

Can someone experienced tell me what ENV is?

Thanks a lot!