labels function creates a vector of labels associated with
a user-defined format.
# S3 method for fmt labels(object, ...)
A user-defined format of class "fmt".
A vector of label values.
condition function creates a condition as part of a format
definition. Each condition has a label as part of its definition.
labels function extracts the labels from the conditions and
returns them as a vector. While the labels will typically be of type
character, they can be of any data type. See the
function help for further details.