The following standard comparison operators are supported in GEL and have the obvious meaning:
	==, >=,
	<=, !=,
	<>, <,
	>.  They return true or
	false.
	The operators
	!= and <> are the same
	thing and mean "is not equal to".
	GEL also supports the operator
	<=>, which returns -1 if left side is
	smaller, 0 if both sides are equal, 1 if left side is larger.
      
	Normally = is translated to == if
	it happens to be somewhere where GEL is expecting a condition such as
	in the if condition.  For example
	
if a=b then c if a==b then c
	are the same thing in GEL.  However you should really use
	== or := when you want to compare
	or assign respectively if you want your code to be easy to read and
	to avoid mistakes.
      
	All the comparison operators (except for the
	<=> operator, which
	behaves normally), are not strictly binary operators, they can in fact
	be grouped in the normal mathematical way, e.g.:
	(1<x<=y<5) is
	a legal boolean expression and means just what it should, that is
	(1<x and x≤y and y<5)
      
	To build up logical expressions use the words not,
	and, or, xor.
	The operators or and and are
special beasts as they evaluate their arguments one by one, so the usual trick
for conditional evaluation works here as well. For example, 1 or a=1 will not set
a=1 since the first argument was true.