new_contents: """Defines classes to represent a cDAL dataset"""
  from enum import Enum
  
  
  class ModelFieldType(Enum):
      """Specifies the possible types for a model field"""
      PRIMARY_KEY = 'PrimaryKey'
      FOREIGN_KEY = 'ForeignKey'
      INTEGER = 'Integer'
      REAL = 'Real'
      TEXT = 'Text'
      BLOB = 'Blob'
  
  
  class Dataset:
      """Represents a dataset to be stored in a single database"""
  
      def __init__(self, name, models):
          self.name = name
          self.models = models
  
      def __repr__(self):
          return 'Dataset(name={},models={})'.format(self.name, self.models)
  
  
  class Model:
      """Represents a model corresponding to a single database table"""
  
      def __init__(self, name, fields, type_name=None, table_name=None):
          self.name = name
          self.fields = fields
          self._type_name = type_name
          self._table_name = table_name
  
      def __repr__(self):
          return 'Model(name={}, fields={})'.format(self.name, self.fields)
  
      def get_c_type(self):
          """Returns the name of the model's C struct type"""
          if self._type_name:
              c_type = self._type_name
          else:
              c_type = self.name
  
          return c_type
  
      def get_table_name(self):
          """Returns the name of the model's database table"""
          if self._table_name:
              table_name = self._table_name
          else:
              table_name = self.name
  
          return table_name
  
  
  class ModelField:
      """Represents a field of a model corresponding to a single database table column"""
  
      def __init__(self, name, field_type, max_length=0):
          self.name = name
          self.field_type = field_type
          self.max_length = max_length
  
      def __repr__(self):
          return 'ModelField(name={},field_type={},max_length={})'.format(
              self.name, self.field_type, self.max_length)
  
subject: Create initial data model