How an electroscope can be charged through conduction?

An electroscope is used to detect the charge on a body. A plastic comb is taken and it is rubbed on hair. Now, the plastic comb gets charged. The comb is touched with the electroscope plate. The static charges which are developed on the comb travels down the conducting wire and reach the two leaves of aluminium foil. Similar charges are acquired by both the leaves and as a result, they repel each other. Thus, the method of charging an uncharged body by bringing another charged body directly in contact is called charging by conduction. By this way, an electroscope can be charged through conduction.