g to the present invention; FIG. 2 is a longitudinal sectional view showing a condition where the foreign matter is held by the wire shown in FIG. 1; FIGS. 3A and 3B are a plan view and a side view of retaining means included in the wire shown in FIG. 1, respectively; FIGS. 4 to 8 are longitudinal sectional views for sequentially illustrating the steps of a using method for the wire shown in FIG.