input: Write a python function to fetch all rows from a table in an SQLite database and return them.
  assert fetch_all_rows('database.db', 'table') == [(1, 'Alice'), (2, 'Bob'), (3, 'Charlie')]
  assert fetch_all_rows('database.db', 'users') == [(1, 'John'), (2, 'Doe')]
  assert fetch_all_rows('database.db', 'products') == [(101, 'Laptop'), (102, 'Smartphone')]
output: def fetch_all_rows(db_name, table_name):
      import sqlite3
      conn = sqlite3.connect(db_name)
      cursor = conn.cursor()
      cursor.execute(f"SELECT * FROM {table_name}")
      rows = cursor.fetchall()
      conn.close()
      return rows