Make xmlast tostring easier to debug

Update samples to work with and without lxml (hopefully)

pypeg2/xmlast.py

@@ -120,14 +120,15 @@ def thing2xml(thing, pretty=False, object_names=False):
     tree = create_tree(thing, None, object_names)
     try:
         if lxml:
-            return etree.tostring(tree, pretty_print=pretty)
+            txt = etree.tostring(tree, pretty_print=pretty)
     except NameError:
         if __debug__:
             if pretty:
                 warnings.warn("lxml is needed for pretty printing",
                         ImportWarning)
         etree.indent(tree)
-        return etree.tostring(tree)
+        txt = etree.tostring(tree)
+    return txt
 
 
 def create_thing(element, symbol_table):

samples/sample1.py

@@ -58,8 +58,9 @@ pyPEG contains an XML backend, too:
 
 >>> del f[2]
 >>> from pypeg2.xmlast import thing2xml
+>>> import sys
 >>> xml = thing2xml(f, pretty=True)
->>> print(xml.decode()) # doctest: +ELLIPSIS
+>>> print(xml.decode(), end="") # doctest: +ELLIPSIS
 <Function typing="int" name="f">
   <Parameters>
     <Parameter typing="int" name="a".../>
@@ -68,7 +69,6 @@ pyPEG contains an XML backend, too:
   <Instruction>do_this</Instruction>
   <Instruction>do_that</Instruction>
 </Function>
-<BLANKLINE>
 
 
 The XML backend can read XML text and create things:

samples/sample2.py

@@ -65,7 +65,6 @@ pyPEG contains an XML backend, too:
   </Section>
   <Section name="Number 3".../>
 </IniFile>
-<BLANKLINE>
 
 In this sample the tree contains named objects only. Then we can output object
 names as tag names. Spaces in names will be translated into underscores.
@@ -82,7 +81,6 @@ names as tag names. Spaces in names will be translated into underscores.
   </Number_2>
   <Number_3.../>
 </IniFile>
-<BLANKLINE>
 """
 
 from __future__ import unicode_literals, print_function