Function: shift
Section: operators
C-Name: gshift
Prototype: GL
Help: shift(x,n): shift x left n bits if n>=0, right -n bits if
 n<0.
Doc: shifts $x$ componentwise left by $n$ bits if $n\ge0$ and right by $|n|$
 bits if $n<0$. May be abbreviated as $x$ \kbd{<<} $n$ or $x$ \kbd{>>} $(-n)$.
 A left shift by $n$ corresponds to multiplication by $2^n$. A right shift of an
 integer $x$ by $|n|$ corresponds to a Euclidean division of $x$ by $2^{|n|}$
 with a remainder of the same sign as $x$, hence is not the same (in general) as
 $x \kbd{\bs} 2^n$.
