input: Write a function to compute the average salary of people from a given CSV file named 'salary.csv'. The function should return the average salary as a float. If the CSV file is empty or there are no salaries to compute, the function should return 0.0.
  assert get_average_salary('salary.csv')==2000.0
  assert get_average_salary('empty_salary.csv')==0.0
  assert get_average_salary('single_salary.csv')==5000.0
  assert get_average_salary('mixed_salary.csv')==3500.0
  assert get_average_salary('missing_salary.csv')==0.0
output: def get_average_salary(filename):
      try:
          with open(filename, 'r') as file:
              lines = file.readlines()
              if not lines:
                  return 0.0
              salaries = [float(line.strip()) for line in lines if line.strip()]
              if not salaries:
                  return 0.0
              return sum(salaries) / len(salaries)
      except FileNotFoundError:
          return 0.0