Describe the bug

Cannot translate rbi to rbs if there is a keyword such as public before def.

#: () -> String 
public def bar = 'bar'

To Reproduce
Spoom version: '1.7.4'

example.rb: before

class Example
  #: () -> String
  public def bar = 'bar'
end

Steps to reproduce the behavior:

1. bundle exec spoom srb sigs translate --from rbs --to rbi example.rb
2. Nothing changes.

Expected behavior

example.rb: after(expected)

class Example
  sig { returns(String) }
  public def bar = 'bar'
end

Additional Information

We use a gem called alt_memery for memoizing.

When using this one, we would be happy if we could support the same, since the keyword memoize comes before def as follows.

#: () -> String 
memoize def foo 
  'foo' 
end