input: Write a function to convert a given SQL statement into a Python Pandas DataFrame. The function should take the SQL statement as a string and the database connection as an argument, and return the resulting DataFrame.
  assert convert_sql_to_df("SELECT * FROM book;", conn).equals(pd.read_sql_query("SELECT * FROM book;", conn))==True
output: def convert_sql_to_df(sql_statement, conn):
      return pd.read_sql_query(sql_statement, conn)