Upper case variable names in functions causes ruby error: dynamic constant assignment

Python
```py
def f():
  CODES = {"KEY": 1}
  return CODES
```
becomes
```ruby
def f()
  CODES = {"KEY" => 1}
end
```
Ruby complains that `CODES` is a constant, when it was a local variable in Python.
```
foo.rb:2: dynamic constant assignment
  CODES = {"KEY" => 1}
```