input: Write a function named `generate_fake_data` that generates sample data for a web application using Python's faker library. The output should contain three columns of data: name, email, and age. The function should generate 10 rows of data.
  
  assert generate_fake_data()==None
  # The output will be printed directly as specified in the function code.
output: def generate_fake_data():
      from faker import Faker
      fake = Faker()
      for _ in range(10):
          print(fake.name(), fake.email(), fake.random_int(min=18, max=80))