/// <summary>
/// Appends a subsequence of the specified character sequence to this writer.
///
/// <para> An invocation of this method of the form <tt>out.append(csq, start,
/// end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
/// exactly the same way as the invocation
///
/// <pre>
/// out.write(csq.subSequence(start, end).toString()) </pre>
///
/// </para>
/// </summary>
/// <param name="csq">
/// The character sequence from which a subsequence will be
/// appended. If <tt>csq</tt> is <tt>null</tt>, then characters
/// will be appended as if <tt>csq</tt> contained the four
/// characters <tt>"null"</tt>.
/// </param>
/// <param name="start">
/// The index of the first character in the subsequence
/// </param>
/// <param name="end">
/// The index of the character following the last character in the
/// subsequence
/// </param>
/// <returns> This writer
/// </returns>
/// <exception cref="IndexOutOfBoundsException">
/// If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
/// is greater than <tt>end</tt>, or <tt>end</tt> is greater than
/// <tt>csq.length()</tt>
///
/// @since 1.5 </exception>
public override PrintWriter Append(CharSequence csq, int start, int end)
{
CharSequence cs = (csq == null ? "null" : csq);
Write(cs.SubSequence(start, end).ToString());
return(this);
}
/// <summary>
/// Appends a subsequence of the specified character sequence to this output
/// stream.
///
/// <para> An invocation of this method of the form <tt>out.append(csq, start,
/// end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
/// exactly the same way as the invocation
///
/// <pre>
/// out.print(csq.subSequence(start, end).toString()) </pre>
///
/// </para>
/// </summary>
/// <param name="csq">
/// The character sequence from which a subsequence will be
/// appended. If <tt>csq</tt> is <tt>null</tt>, then characters
/// will be appended as if <tt>csq</tt> contained the four
/// characters <tt>"null"</tt>.
/// </param>
/// <param name="start">
/// The index of the first character in the subsequence
/// </param>
/// <param name="end">
/// The index of the character following the last character in the
/// subsequence
/// </param>
/// <returns> This output stream
/// </returns>
/// <exception cref="IndexOutOfBoundsException">
/// If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
/// is greater than <tt>end</tt>, or <tt>end</tt> is greater than
/// <tt>csq.length()</tt>
///
/// @since 1.5 </exception>
public virtual PrintStream Append(CharSequence csq, int start, int end)
{
CharSequence cs = (csq == null ? "null" : csq);
Write(cs.SubSequence(start, end).ToString());
return(this);
}