input: Write a python function to find all leap years in a given range.
  assert find_leap_years(2001, 2026) == [2004, 2008, 2012, 2016, 2020, 2024]
  assert find_leap_years(1990, 2000) == [1992, 1996, 2000]
  assert find_leap_years(1800, 1900) == [1804, 1808, 1812, 1816, 1820, 1824, 1828, 1832, 1836, 1840, 1844, 1848, 1852, 1856, 1860, 1864, 1868, 1872, 1876, 1880, 1884, 1888, 1892, 1896]
output: def find_leap_years(start_year, end_year):
      leap_years = []
      for year in range(start_year, end_year + 1):
          if (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0):
              leap_years.append(year)
      return leap_years