input: Write a python function to format a given birth year into a string formatted as "YYYY-01-01".
  assert formatYear(1990) == "1990-01-01"
  assert formatYear(2023) == "2023-01-01"
  assert formatYear(1985) == "1985-01-01"
output: def formatYear(year):
      return f"{year}-01-01"