def process_if(exp, _parent)
      children = exp.children
      increase_statement_count_by(children[1])
      increase_statement_count_by(children[2])
      decrease_statement_count
      process(exp)
    end
def process_if(exp, _parent)
      children = exp.children
      increase_statement_count_by(children[1])
      increase_statement_count_by(children[2])
      decrease_statement_count
      process(exp)
    end
Handles `if` nodes.

 An input example that would trigger this method would be:

 if a > 5 && b < 3
   puts 'bingo'
 else
   3
 end

 Counts the `if` body as one statement and the `else` body as another statement.

 At the end we subtract one statement because the surrounding context was already counted
 as one (e.g. via `process_def`).

 `children[1]` refers to the `if` body (so `puts 'bingo'` from above) and
 `children[2]` to the `else` body (so `3` from above), which might be nil.