input: Write a function to convert a given SQL statement into a Python Pandas DataFrame. The function should take a SQL statement as an argument, execute it using a database connection, and return the result as a Pandas DataFrame.
  assert convert_sql_to_df("SELECT * FROM book;", conn).equals(pd.read_sql_query("SELECT * FROM book;", conn))
  assert convert_sql_to_df("SELECT title, author FROM book;", conn).equals(pd.read_sql_query("SELECT title, author FROM book;", conn))
  assert convert_sql_to_df("SELECT * FROM book WHERE id = 1;", conn).equals(pd.read_sql_query("SELECT * FROM book WHERE id = 1;", conn))
  assert convert_sql_to_df("SELECT price FROM book;", conn).equals(pd.read_sql_query("SELECT price FROM book;", conn))
  assert convert_sql_to_df("SELECT title, price FROM book WHERE author = 'J.K. Rowling';", conn).equals(pd.read_sql_query("SELECT title, price FROM book WHERE author = 'J.K. Rowling';", conn))
output: def convert_sql_to_df(sql_statement, conn):
      return pd.read_sql_query(sql_statement, conn)