code: def as_singular(result_key):
      
      if result_key.endswith('ies'):
          return re.sub('ies$', 'y', result_key)
      elif result_key.endswith('uses'):
          return re.sub("uses$", "us", result_key)
      elif result_key.endswith('addresses'):  # Special case for '*addresses'
          return result_key[:-2]
      elif result_key.endswith('s'):
          return result_key[:-1]
      else:
          return result_key
docs: Given a result key, return in the singular form