count() now has a 4th parameter too. Also rephrased the docs for find
to use the same, better words to explain start/end.
diff --git a/Doc/lib/libstring.tex b/Doc/lib/libstring.tex
index 930ce22..3d0631a 100644
--- a/Doc/lib/libstring.tex
+++ b/Doc/lib/libstring.tex
@@ -110,14 +110,11 @@
\end{funcdesc}
\begin{funcdesc}{find}{s\, sub\optional{\, start\optional{\,end}}}
-Return the lowest index in \var{s} not smaller than \var{start} and not
-greater than \var{end} where the substring \var{sub} is found. Return
-\code{-1} when \var{sub} does not occur as a substring of \var{s} with
-index at least \var{start} and less than \var{end}.
-If \var{start} is omitted, it defaults to \code{0}. If \var{start} is
-negative, \code{len(\var{s})} is added.
-If \var{end} is omitted, it defaults to \code{len(\var{s})}. If
-\var{end} is negative, \code{len(\var{s})} is added.
+Return the lowest index in \var{s} where the substring \var{sub} is
+found such that \var{sub} is wholly contained in
+\code{\var{s}[\var{start}:\var{end}]}. Return -1 on failure.
+Defaults for \var{start} and \var{end} and interpretation of negative
+values is the same as for slices.
\end{funcdesc}
\begin{funcdesc}{rfind}{s\, sub\optional{\, start\optional{\,end}}}
@@ -134,11 +131,11 @@
not found.
\end{funcdesc}
-\begin{funcdesc}{count}{s\, sub\optional{\, start}}
+\begin{funcdesc}{count}{s\, sub\optional{\, start\optional{\,end}}}
Return the number of (non-overlapping) occurrences of substring
-\var{sub} in string \var{s} with index at least \var{start}.
-If \var{start} is omitted, it defaults to \code{0}. If \var{start} is
-negative, \code{len(\var{s})} is added.
+\var{sub} in string \code{\var{s}[\var{start}:\var{end}]}.
+Defaults for \var{start} and \var{end} and interpretation of negative
+values is the same as for slices.
\end{funcdesc}
\begin{funcdesc}{lower}{s}
diff --git a/Doc/libstring.tex b/Doc/libstring.tex
index 930ce22..3d0631a 100644
--- a/Doc/libstring.tex
+++ b/Doc/libstring.tex
@@ -110,14 +110,11 @@
\end{funcdesc}
\begin{funcdesc}{find}{s\, sub\optional{\, start\optional{\,end}}}
-Return the lowest index in \var{s} not smaller than \var{start} and not
-greater than \var{end} where the substring \var{sub} is found. Return
-\code{-1} when \var{sub} does not occur as a substring of \var{s} with
-index at least \var{start} and less than \var{end}.
-If \var{start} is omitted, it defaults to \code{0}. If \var{start} is
-negative, \code{len(\var{s})} is added.
-If \var{end} is omitted, it defaults to \code{len(\var{s})}. If
-\var{end} is negative, \code{len(\var{s})} is added.
+Return the lowest index in \var{s} where the substring \var{sub} is
+found such that \var{sub} is wholly contained in
+\code{\var{s}[\var{start}:\var{end}]}. Return -1 on failure.
+Defaults for \var{start} and \var{end} and interpretation of negative
+values is the same as for slices.
\end{funcdesc}
\begin{funcdesc}{rfind}{s\, sub\optional{\, start\optional{\,end}}}
@@ -134,11 +131,11 @@
not found.
\end{funcdesc}
-\begin{funcdesc}{count}{s\, sub\optional{\, start}}
+\begin{funcdesc}{count}{s\, sub\optional{\, start\optional{\,end}}}
Return the number of (non-overlapping) occurrences of substring
-\var{sub} in string \var{s} with index at least \var{start}.
-If \var{start} is omitted, it defaults to \code{0}. If \var{start} is
-negative, \code{len(\var{s})} is added.
+\var{sub} in string \code{\var{s}[\var{start}:\var{end}]}.
+Defaults for \var{start} and \var{end} and interpretation of negative
+values is the same as for slices.
\end{funcdesc}
\begin{funcdesc}{lower}{s}