def to_xml_string(str = '')
      str << '<xdr:oneCellAnchor>'
      str << '<xdr:from>'
      from.to_xml_string(str)
      str << '</xdr:from>'
      str << ('<xdr:ext cx="' << ext[:cx].to_s << '" cy="' << ext[:cy].to_s << '"/>')
      @object.to_xml_string(str)
      str << '<xdr:clientData/>'
      str << '</xdr:oneCellAnchor>'
    end
def to_xml_string(str = '')
      str << '<xdr:oneCellAnchor>'
      str << '<xdr:from>'
      from.to_xml_string(str)
      str << '</xdr:from>'
      str << ('<xdr:ext cx="' << ext[:cx].to_s << '" cy="' << ext[:cy].to_s << '"/>')
      @object.to_xml_string(str)
      str << '<xdr:clientData/>'
      str << '</xdr:oneCellAnchor>'
    end
Serializes the object
 @param [String] str
 @return [String]