Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. For values of ch in the range from 0 to 0xFFFF (inclusive), the index returned is the largest value k such that:

 (this.charAt(k) == ch) && (k <= fromIndex)

is true. For other values of ch, it is the largest value k such that:

 (this.codePointAt(k) == ch) && (k <= fromIndex)

is true. In either case, if no such character occurs in this string at or before position fromIndex, then -1 is returned.

All indices are specified in char values (Unicode code units).

Parameters:

ch a character (Unicode code point).

fromIndex the index to start the search from. There is no restriction on the value of fromIndex. If it is greater than or equal to the length of this string, it has the same effect as if it were equal to one less than the length of this string: this entire string may be searched. If it is negative, it has the same effect as if it were -1: -1 is returned.

Returns: the index of the last occurrence of the character in the character sequence represented by this object that is less than or equal to fromIndex, or -1 if the character does not occur before that point.

`ch`		a character (Unicode code point).
`fromIndex`		the index to start the search from. There is no restriction on the value of `fromIndex`. If it is greater than or equal to the length of this string, it has the same effect as if it were equal to one less than the length of this string: this entire string may be searched. If it is negative, it has the same effect as if it were -1: -1 is returned.