When building a benvo iteratively the base benvo allows you to start with no bef data constructed a priori and build up from
subject data that contains spatial and/or temporal raw data in the form of sf
structures or Date
columns.
base_benvo(subject_data, by, ...)
data.frame containing subject level covariates.
optional key
optional arguments for specifying date-time columns see set_datetime_cols
a benvo with attribute base = TRUE