def forward(self, j=<NUM_LIT:1>):
if j < <NUM_LIT:0>:<EOL><INDENT>return self.backward(-j)<EOL><DEDENT>self.__i += j<EOL>return self[self.__i-j:self.__i]<EOL>
Move forward by j steps.

        >>> b = Buffer('abcdef')
        >>> b.forward(3)
        'abc'
        >>> b.forward(-2)
        'bc'