group_by_epi_df_methods.R

# These methods (and maybe some others in methods-epi_df.R) are here to augment
# `?dplyr_extending` implementations to get the correct behavior on grouped
# `epi_df`s. It would be nice if there were a way to replace these with a
# generic core that automatically fixed all misbehaving methods; see
# brainstorming within Issue #223.