fixed the documentation of vertices and latticePoints

M2/Macaulay2/packages/NormalToricVarieties/DivisorsDocumentation.m2

@@ -2018,16 +2018,15 @@ doc ///
             Cartier divisor is a lattice polytope.  Given a torus-invariant
             Cartier divisor on a normal toric variety, this method returns an
             integer matrix whose columns correspond to the vertices of the
-            associated lattice polytope.  For a non-effective Cartier divisor,
-            this methods returns @TO null@.  When the divisor is ample,
+	    associated lattice polytope. When the divisor is ample,
             the normal fan the corresponding polytope equals the fan
             associated to the normal toric variety.
         Text
             On the projective plane, the associate polytope is either empty,
 	    a point, or a triangle.
         Example  
     	    PP2 = toricProjectiveSpace 2;
-    	    assert (null === vertices (-PP2_0))
+	    assert (vertices (-PP2_0) == 0)
     	    vertices (0*PP2_0)
     	    assert isAmple PP2_0
     	    V1 = vertices (PP2_0)
@@ -2082,14 +2081,13 @@ doc ///
   	    Cartier divisor is a lattice polytope.  Given a torus-invariant
   	    Cartier divisor on a normal toric variety, this method returns an
   	    integer matrix whose columns correspond to the lattices points
-  	    contained in the associated polytope.  For a non-effective Cartier
-  	    divisor, this method returns @TO null@.
+	    contained in the associated polytope.
         Text  
             On the projective plane, the associate polytope is either empty, a
    	    point, or a triangle.
         Example
             PP2 = toricProjectiveSpace 2;
-    	    assert (null === vertices (-PP2_0))
+	    assert (vertices (-PP2_0) == 0)
     	    latticePoints (0*PP2_0)
     	    assert isAmple PP2_0
     	    V1 = latticePoints (PP2_0)