def add_custom_attributes(UserPoolId=None, CustomAttributes=None):
    """
    Adds additional user attributes to the user pool schema.
    See also: AWS API Documentation
    
    
    :example: response = client.add_custom_attributes(
        UserPoolId='string',
        CustomAttributes=[
            {
                'Name': 'string',
                'AttributeDataType': 'String'|'Number'|'DateTime'|'Boolean',
                'DeveloperOnlyAttribute': True|False,
                'Mutable': True|False,
                'Required': True|False,
                'NumberAttributeConstraints': {
                    'MinValue': 'string',
                    'MaxValue': 'string'
                },
                'StringAttributeConstraints': {
                    'MinLength': 'string',
                    'MaxLength': 'string'
                }
            },
        ]
    )
    
    
    :type UserPoolId: string
    :param UserPoolId: [REQUIRED]
            The user pool ID for the user pool where you want to add custom attributes.
            

    :type CustomAttributes: list
    :param CustomAttributes: [REQUIRED]
            An array of custom attributes, such as Mutable and Name.
            (dict) --Contains information about the schema attribute.
            Name (string) --A schema attribute of the name type.
            AttributeDataType (string) --The attribute data type.
            DeveloperOnlyAttribute (boolean) --Specifies whether the attribute type is developer only.
            Mutable (boolean) --Specifies whether the attribute can be changed once it has been created.
            Required (boolean) --Specifies whether a user pool attribute is required. If the attribute is required and the user does not provide a value, registration or sign-in will fail.
            NumberAttributeConstraints (dict) --Specifies the constraints for an attribute of the number type.
            MinValue (string) --The minimum value of an attribute that is of the number data type.
            MaxValue (string) --The maximum value of an attribute that is of the number data type.
            StringAttributeConstraints (dict) --Specifies the constraints for an attribute of the string type.
            MinLength (string) --The minimum length of an attribute value of the string type.
            MaxLength (string) --The maximum length of an attribute value of the string type.
            
            

    :rtype: dict
    :return: {}
    
    
    """
    pass
