This function lets you add more than one variable at a time to a dataset.
If you have multiple variables to add, this function will be faster than
doing ds$var <- value
assignment because it doesn't refresh the
dataset's state in between variable POST requests.
addVariables(dataset, ...)
dataset
with the new variables added (invisibly)
a CrunchDataset
VariableDefinition
s or a list of
VariableDefinitions.