Describe the bug

In this example, the method type_updated? will be flagged as unused, despite being called as a proc.

after_update :notify, if: :type_updated?

def type_updated?
  # contents irrelevant
end

def notify
  # this is a placeholder to demonstrate the issue.
end 

The commonness of this pattern means that deadcode results can be flooded with these examples.

To Reproduce
Spoom v1.6.1

See above code snippet, add it to to any Rails model

Run bundle exec spoom deadcode

Expected behavior
Symbolic references to a method mean that it will be considered used.

For deadcode output, this change would mean the method will be

1. Excluded (works fine for my purposes), or
2. Moved to a separate report section, or
3. Configurable as to whether or not it appears in the report (and excluded by default)