AlCl3 is lewis acid. Explain how?

For AlCl3 to be a Lewis acid, it would have to react in such a way that it accepted a lone pair from some other atom or molecule from a Lewis base. AlCl3 has an electron-deficient aluminum atom. It has only six electrons in its valence shell. It readily accepts electrons from other atoms, in an attempt to get a full valence shell of eight electrons.