code: def _check_ddl_statements(value):
      
      if not all(isinstance(line, six.string_types) for line in value):
          raise ValueError("Pass a list of strings")
  
      if any("create database" in line.lower() for line in value):
          raise ValueError("Do not pass a 'CREATE DATABASE' statement")
  
      return tuple(value)
docs: Validate DDL Statements used to define database schema.
  
      See
      https://cloud.google.com/spanner/docs/data-definition-language
  
      :type value: list of string
      :param value: DDL statements, excluding the 'CREATE DATABSE' statement
  
      :rtype: tuple
      :returns: tuple of validated DDL statement strings.
      :raises ValueError:
          if elements in ``value`` are not strings, or if ``value`` contains
          a ``CREATE DATABASE`` statement.