Returns the left-hand argument of a binary application.
DESCRIPTION
A call to lhand t returns x in those situations where t is of
the form ``f x y``.
FAILURE
Fails if the argument is not of the required form.
EXAMPLE
- lhand ``3 + 2``;
> val it = ``3`` : term
COMMENTS
The name lhand is an abbreviation of “left-hand”, but rand is
so-named as an abbreviation of “operand”. Nonetheless, rand does
return the right-hand argument of a binary application.