input: Write a python function to fetch and print all customer details from a MySQL database.
  assert fetch_customer_details() is None
output: def fetch_customer_details():
      import mysql.connector
  
      # Establish a connection to the MySQL database
      conn = mysql.connector.connect(
          host='your_host',  # e.g., 'localhost' or '127.0.0.1'
          user='your_username',
          password='your_password',
          database='your_database'
      )
      
      cursor = conn.cursor()
  
      # Execute a query to fetch all customer details
      cursor.execute("SELECT * FROM customers")
  
      # Fetch all rows from the executed query
      rows = cursor.fetchall()
  
      # Print the customer details
      for row in rows:
          print(row)
  
      # Close the cursor and connection
      cursor.close()
      conn.close()