class ReeDatetime::YearsDiff

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
  y_delta = s_delta / YEAR_SECONDS
  opts[:precision] = 0
  round_helper(
    y_delta,
    **slice(opts, [:precision, :round_mode])
  ).to_i
end