Remove line meant to test trailing whitespace since that kind of whitespace is

automatically removed.

Also annotate what each line is meant to test.

Misc/Vim/syntax_test.py

 """Test file for syntax highlighting of editors.
 
 Meant to cover a wide range of different types of statements and expressions.
-Not necessarily sensical.
+Not necessarily sensical or comprehensive (assume that if one exception is
+highlighted that all are, for instance).
+
+Highlighting extraneous whitespace at the end of the line is not represented
+here as all trailing whitespace is automatically removed from .py files in the
+repository.
 
 """
-assert True
-def foo(): pass
-foo()  # Uncoloured
-while False: pass
-1 and 2
-if False: pass
-from sys import path
 # Comment
-# XXX catch your attention
-'single-quote', u'unicode'
+# OPTIONAL: XXX catch your attention
+
+# Statements
+assert True # keyword
+def foo():  # function definition
+    return []
+class Bar(object):  # Class definition
+    pass
+foo()  # UNCOLOURED: function call
+while False:  # 'while'
+    continue
+for x in foo():  # 'for'
+    break
+if False: pass  # 'if'
+elif False: pass
+else False: pass
+from sys import path as thing  # Import
+
+# Constants
+'single-quote', u'unicode' # Strings of all kinds; prefixes not highlighted
 "double-quote"
 """triple double-quote"""
 '''triple single-quote'''
@@ -23,14 +39,19 @@ ur'unicode raw'
 '\04'  # octal
 '\xFF' # hex
 '\u1111' # unicode character
-1
+1  # Integral
 1L
-1.0
+1.0  # Float
 .1
-1+2j
-[]  # Uncoloured
-{}  # Uncoloured
-()  # Uncoloured
-all
-GeneratorExit
-trailing_whitespace = path
+1+2j  # Complex
+
+# Expressions
+1 and 2 or 3  # Boolean operators
+2 < 3  # UNCOLOURED: comparison operators
+spam = 42  # UNCOLOURED: assignment
+2 + 3  # UNCOLOURED: number operators
+[]  # UNCOLOURED: list
+{}  # UNCOLOURED: dict
+(1,)  # UNCOLOURED: tuple
+all  # Built-in functions
+GeneratorExit  # Exceptions