Utility functions for keyed objects which are implemented with class
keyed_df. Keyed object should be a data frame which inherits from
keyed_df and contains a data frame of keys in attribute 'keys'.
is_keyed_df(.tbl) is.keyed_df(.tbl) # S3 method for keyed_df print(x, ...) # S3 method for keyed_df [(x, i, j, ...)
Object to check.
Object to print or extract elements.
Further arguments passed to or from other methods.