Added a new error exception "NotShelveFileError" to handle the case in src.pd_extras.dataframe_with_info.import_df_with_info_from_file function where the filename is not a file created using shelve module.
Added tests for src.pd_extras.dataframe_with_info.import/export_df_with_info functions.
Added two fixtures for creating generic files with 'shelve' module and the builtin functions.
Added a new error exception "NotShelveFileError" to handle the case in
src.pd_extras.dataframe_with_info.import_df_with_info_from_file
function where the filename is not a file created using shelve module.Added tests for
src.pd_extras.dataframe_with_info.import/export_df_with_info
functions. Added two fixtures for creating generic files with 'shelve' module and the builtin functions.