Appends the specified character to this Appendable.

  Appends the specified character to this Appendable.
Returns: A reference to this Appendable
Parameters:
- c - The character to append
Throws:
- IOException - If an I/O error occurs

  Appends the specified character sequence to this Appendable.

  Appends the specified character sequence to this Appendable.

Depending on which class implements the character sequence csq, the entire sequence may not be appended. For instance, if csq is a CharBuffer then the subsequence to append is defined by the buffer's position and limit.
Returns: A reference to this Appendable
Parameters:
- csq - The character sequence to append. If csq is null, then the four characters "null" are appended to this Appendable.
Throws:
- IOException - If an I/O error occurs

  Appends a subsequence of the specified character sequence to this Appendable.

  Appends a subsequence of the specified character sequence to this Appendable.

An invocation of this method of the form out.append(csq, start, end) when csq is not null, behaves in exactly the same way as the invocation

     out.append(csq.subSequence(start, end)) 

Returns: A reference to this Appendable
Parameters:
- csq - The character sequence from which a subsequence will be appended. If csq is null, then characters will be appended as if csq contained the four characters "null".
- start - The index of the first character in the subsequence
- end - The index of the character following the last character in the subsequence
Throws:
- IndexOutOfBoundsException - If start or end are negative, start is greater than end, or end is greater than csq.length()
- IOException - If an I/O error occurs