input: from typing import List
  
  def generate_sample_data(num_samples: int) -> List[str]:
      """ Generate sample data for a web application using Python's faker library.
      The output should contain three columns of data: name, email, and age.
      >>> generate_sample_data(3)
      """
output:     
      from faker import Faker
      fake = Faker()
      data = []
      for _ in range(num_samples):
          name = fake.name()
          email = fake.email()
          age = fake.random_int(min=18, max=65)
          data.append(f"{name},{email},{age}")
      return data
  