input: Write a function to generate sample data for a web application using Python's faker library. The function should generate and print three columns of data: name, email, and age. The age should be randomly generated between 18 and 60. The function should accept an integer parameter 'n' that specifies the number of rows of data to generate. If 'n' is not provided, the function should generate 10 rows of data by default.
  
  def generate_sample_data(n=10):
   from faker import Faker
   fake = Faker()
   for _ in range(n):
   print(fake.name(), fake.email(), fake.random_int(min=18, max=60))
  
  assert generate_sample_data(2) is None  # Output should be two rows of name, email, and age
  assert generate_sample_data() is None  # Output should be ten rows of name, email, and age
output: def generate_sample_data(n=10):
   from faker import Faker
   fake = Faker()
   for _ in range(n):
   print(fake.name(), fake.email(), fake.random_int(min=18, max=60))