def METHOD_NAME(policy, role, service_account):
  """Add a role to a service account. Returns whether or not changes were
  made."""
  binding = _get_or_insert_iam_binding(policy, role)
  service_account_member = 'serviceAccount:' + service_account
  if service_account_member not in binding['members']:
    binding['members'].append(service_account_member)
    return True
  return False