names(data).
Throws error if stops=TRUE, else returns FALSE if some variable name is not present.
all_names_present(data, var.names, stops = TRUE, msg = NULL)c("var1", "var2")%%VARS%% in message string and the missing
variable names will be inserted there (quoted, separated by comma, e.g.
'var1', 'var2' --- no leading or tracing white space).robust_values