Rather than setting the method parameter to an instance variable that is used in the `command_line_options` method on the next line, I think it would be better to just set the churn command at initialization.  I think it would be simpler that way.

e.g.


@churn_command = churn_command(options)

# or some variation on this
def churn_command(options)
  ['churn --yaml', options[:minimum_churn_count]].compact.join(' ')
end

def emit
  @output = system(@churn_command)