Lookups return types that can not be stored in dynamo

[andrewkrug]

#"warm_since": is_warm.warm_since, # Issues with dynamo types
#"warm_for":   is_warm.warm_for, # Issues with dynamo types
#"dmesg":      get_dmesg, # Issues with dynamo types

Error is:

TypeError: Float types are not supported. Use Decimal types instead.

ClientError: An error occurred (ValidationException) when calling the PutItem operation: One or more parameter values were invalid: An AttributeValue may not contain an empty string