SF patch #797868: Tutorial, sec. 5.1.4 could contain an extra example

(Revised from the original patch contributed by Michal Pasternak.)

Also, make a couple minor fixups elsewhere.

Doc/tut/tut.tex

@@ -122,7 +122,7 @@ written in Python are typically much shorter than equivalent C or
 the high-level data types allow you to express complex operations in a
 single statement;
 \item
-statement grouping is done by indentation instead of begin/end
+statement grouping is done by indentation instead of beginning and ending
 brackets;
 \item
 no variable or argument declarations are necessary.
@@ -517,7 +517,7 @@ magnitude (as a float) or \code{z.real} to get its real part.
 >>> float(a)
 Traceback (most recent call last):
   File "<stdin>", line 1, in ?
-TypeError: can't convert complex to float; use e.g. abs(z)
+TypeError: can't convert complex to float; use abs(z)
 >>> a.real
 3.0
 >>> a.imag
@@ -1925,6 +1925,14 @@ SyntaxError: invalid syntax
 [8, 12, -54]
 \end{verbatim}
 
+List comprehensions are much more flexible than \function{map()} and can be
+applied to functions with more than one argument and to nested functions:
+
+\begin{verbatim}
+>>> [str(round(355/113.0, i)) for i in range(1,6)]
+['3.1', '3.14', '3.142', '3.1416', '3.14159']
+\end{verbatim}
+
 To make list comprehensions match the behavior of \keyword{for}
 loops, assignments to the loop variable remain visible outside
 of the comprehension: