Examples
?- X is 13 << 0.
X = 13
yes
?- X is 13 << 1.
X = 26
yes
?- X is 13 << 2.
X = 52
yes
?- X is 13 << 3.
X = 104
yes
?- X is 13 << 4.
X = 208
yes
?- X is 13 >> 0.
X = 13
yes
?- X is 13 >> 1.
X = 6
yes
?- X is 13 >> 2.
X = 3
yes
?- X is 13 >> 3.
X = 1
yes
?- X is 13 >> 4.
X = 0
yes
?- X is 13 << -1.
X = 6
yes
?- X is 13 << -2.
X = 3
yes
?- X is 13 << -3.
X = 1
yes
?- X is 13 << -4.
X = 0
yes
?- X is 13 >> -1.
X = 26
yes
?- X is 13 >> -2.
X = 52
yes
?- X is 13 >> -3.
X = 104
yes
?- X is 13 >> -4.
X = 208
yes