AssertStructValid checks the fields in the structure and makes sure that they contain valid values as specified by the 'valid' flag.

AssertValid checks to make sure that the given value is in the list of valid values.

IsZero returns whether or not the parameter is the zero value for its type.

NewCloudConfig instantiates a new CloudConfig from the given contents (a string of YAML), returning any error encountered.

CloudConfig encapsulates the entire cloud-config configuration file and maps directly to YAML.