import re


def add_suffix(alias):
  """Adds an int suffix to alias."""
  alias = alias.strip('`')
  m = re.search(r'([0-9]+)$', alias)
  if m:
    suffix = m.group(1)
    alias = alias[:-len(suffix)] + str(int(suffix) + 1)
    return alias
  else:
    return alias + '_1'