Logical shift
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1 << 0  = 0001  =  1
1 << 1  = 0010  =  2
1 << 2  = 0100  =  4
1 << 3  = 1000  =  8

Bitwise AND
-----------

x = 25;      /* 00011001 (16 + 8 + 1) */
y = 1 << 4;   /* 00010000 (1 shifted left by 4 places = 16) */
z = x & y    /* 00010000 */