class ReeDatetime::MonthsDiff

def call(start_time, end_time, **opts)
  s_delta = end_time.to_time.to_i - start_time.to_time.to_i
  raise ArgumentError, "start_time bigger than end_time" if s_delta < 0
  m_delta = s_delta / MONTH_SECONDS
  opts[:precision] = 0
  round_helper(
    m_delta,
    **slice(opts, [:precision, :round_mode])
  ).to_i
end