Replace substring of <code>str</code> with <code>value</code>
@param {String} str String where to replace substring
@param {String} value New substring value
@param {Number} start Start index of substring to replace. May also
be a <code>Range</code> object: in this case, the <code>end</code>
argument is not required
@param {Number} end End index of substring to replace. If ommited,
<code>start</code> argument is used
function(str, value, start, end) {
			if (_.isObject(start) && 'end' in start) {
				end = start.end;
				start = start.start;
			}
			
			if (_.isString(end))
				end = start + end.length;
			
			if (_.isUndefined(end))
				end = start;
			
			if (start < 0 || start > str.length)
				return str;
			
			return str.substring(0, start) + value + str.substring(end);
		}