Add tuple comma when not in BUILD_LIST_n

Fixes issue #57

bin/uncompile.py: --verify now works on a single bytecode file. We will
set the output to be something created by tempfile.mktemps

test/simple_source/expression/03_tuple_assign.py

@@ -0,0 +1,7 @@
+# Github Issue #57 with Python 2.7
+def some_function():
+    return ['some_string']
+
+def some_other_function():
+    some_variable, = some_function()
+    print(some_variable)

uncompyle6/bin/uncompile.py

@@ -5,7 +5,7 @@
 # Copyright (c) 2000-2002 by hartmut Goebel <h.goebel@crazy-compilers.com>
 #
 from __future__ import print_function
-import sys, os, getopt, time
+import sys, os, getopt, tempfile, time
 
 program, ext = os.path.splitext(os.path.basename(__file__))
 
@@ -143,9 +143,12 @@ def main_bin():
         print("No files given", file=sys.stderr)
         usage()
 
-
     if outfile == '-':
-        outfile = None # use stdout
+        if 'do_verify' in options and len(files) == 1:
+            junk, outfile = tempfile.mkstemp(suffix=".pyc",
+                                             prefix=files[0][0:-4]+'-')
+        else:
+            outfile = None # use stdout
     elif outfile and os.path.isdir(outfile):
         out_base = outfile; outfile = None
     elif outfile and len(files) > 1:

uncompyle6/semantics/pysource.py

@@ -51,7 +51,9 @@ methods implement most of the below.
     %D  same as %C but is for left-recursive lists like kwargs which
         goes to epsilon at the beginning. Using %C an extra separator
         with an epsilon appears at the beginning
-    %,  print ',' if last %C only printed one item (for tuples--unused)
+    %,  print ',' if last %C only printed one item. This is mostly for tuples
+        on the LHS of an assignment statement since BUILD_TUPLE_n pretty-prints
+        other tuples.
     %|  tab to current indentation level
     %+ increase current indentation level
     %- decrease current indentation level
@@ -211,7 +213,10 @@ TABLE_DIRECT = {
     'STORE_GLOBAL':	( '%{pattr}', ),
     'STORE_DEREF':	( '%{pattr}', ),
     'unpack':		( '%C%,', (1, maxint, ', ') ),
-    'unpack_w_parens':		( '(%C%,)', (1, maxint, ', ') ),
+
+    # This nonterminal we create on the fly in semantic routines
+    'unpack_w_parens':	( '(%C%,)', (1, maxint, ', ') ),
+
     'unpack_list':	( '[%C]', (1, maxint, ', ') ),
     'build_tuple2':	( '%P', (0, -1, ', ', 100) ),
 
@@ -1812,9 +1817,12 @@ class SourceWalker(GenericASTTraversal, object):
             elif typ == '+':	self.indentMore()
             elif typ == '-':	self.indentLess()
             elif typ == '|':	self.write(self.indent)
-            # no longer used, since BUILD_TUPLE_n is pretty printed:
+            # Used mostly on the LHS of an assignment
+            # BUILD_TUPLE_n is pretty printed and may take care of other uses.
             elif typ == ',':
-                pass
+                if (node.type in ('unpack', 'unpack_w_parens') and
+                    node[0].attr == 1):
+                    self.write(',')
             elif typ == 'c':
                 # FIXME: In Python3 sometimes like from
                 # importfrom