input: Write a function to compute the average salary of people from the dataset 'salary.csv'.
  assert get_average_salary('salary.csv')==2000.0
  assert get_average_salary('salary2.csv')==2500.0
output: def get_average_salary(filename):
      total = 0
      count = 0
      with open(filename, 'r') as file:
          for line in file:
              salary = float(line.strip())
              total += salary
              count += 1
      return total / count