Usage:

x |= y

Assigns x to the value of x | y. It is equivalent to x = x | y. This is often used for enabling bitflags in a bitfield.

#define MY_BITFLAG (1<<0)

var/my_field = 0 // starts disabled
my_field |= MY_BITFLAG // now enabled

If both x and y are /lists, all items in y not already present in x will be added to x.

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