class Roo::Excel2003XML

def cell(row, col, sheet = nil)

cell at the first line and first row.
(1,1), (1,'A'), ('A',1), ('a',1) all refers to the
(1,1) is the upper left corner.
Returns the content of a spreadsheet-cell. 
def cell(row, col, sheet = nil)
  sheet ||= @default_sheet
  read_cells(sheet)
  row, col = normalize(row, col)
  if celltype(row, col, sheet) == :date
    yyyy, mm, dd = @cell[sheet][[row, col]].split('-')
    return Date.new(yyyy.to_i, mm.to_i, dd.to_i)
  end
  @cell[sheet][[row, col]]
end