class Rubocop::Cop::DefWithoutParentheses

def check(tokens, def_sexp)
  if def_sexp[2][0] == :params && def_sexp[2] != EMPTY_PARAMS
    add_offence(:convention, def_sexp[1][-1].lineno, error_message)
  end
end

def error_message
  'Use def with parentheses when there are arguments.'
end