input: Write a python function to create a new table called 'books' in an SQLite database with columns 'title', 'author', 'year', and 'copies'.
  assert create_books_table('library.db')==True
output: def create_books_table(db_name):
      import sqlite3
      try:
          conn = sqlite3.connect(db_name)
          cursor = conn.cursor()
          cursor.execute('''
              CREATE TABLE IF NOT EXISTS books (
                  title TEXT,
                  author TEXT,
                  year INTEGER,
                  copies INTEGER
              )
          ''')
          conn.commit()
          conn.close()
          return True
      except sqlite3.Error as e:
          print(e)
          return False