Question 2 Given that $a, b, c$ are non-zero real numbers, and
$$
M=\frac{a}{|a|}+\frac{b}{|b|}+\frac{c}{|c|}+\frac{a b}{|a b|}+\frac{b c}{|b c|}+\frac{c a}{|c a|}+\frac{a b c}{|a b c|} \text {. }
$$

Find the value of $M$.