Because on both of them you are typing/writing something.
Answer:
In some reductions of aldehydes and ketones, 
donates a pair of electrons. As a result, by the Lewis Theory of acids and bases, can be considered as a base.
Explanation:
When a reducing agent such as 
reduces aldehydes or ketones to alcohol, the ion acts as an intermediary. In other words, these ions are produced in one step but completely consumed in another.
ions are electron-rich; they are attracted to the electron-deficient region of aldehyde and ketone molecules. Each ion has a lone pair of electrons. In each aldehyde and ketone molecule, at least one carbon is bonded with a double bond to an oxygen atom. Oxygen is very electronegative. It would draw the electron pairs away from the carbon atom. As a result, in aldehydes and ketones, carbon atoms with a 
bound are electron-deficient; they carry partial-positive 
charges. The electron-rich ions would be attracted to these electron-deficient carbon atoms.
During the reaction, ions shares its two electrons with the partially-positive carbon atom in the aldehyde or ketone. It does so by forming a 
bond. Even though that's not a complete electron transfer, the Lewis Theory of acids and bases would consider that ion as an electron-pair donor. Because of that, the ion can be called a Lewis base. (Similarly, the aldehyde or ketone that "accepts" the electron-pair would be a Lewis acid.)
