Content
Depending on the cell, the content may be a numeric value such as 365 or
365.25, it may represent a date/datetime in one of Excel's date/datetime
systems, or it may be an index into an internal table of strings.
xlsx_cells()
attempts to infer the correct data type of each cell,
returning its value in the appropriate column (error, logical, numeric,
date, character). In case this cleverness is unhelpful, the unparsed value
and type information is available in the 'content' and 'data_type' columns.