fails:String#upto passes successive values, starting at self and ending at other_string, to the block
fails:String#upto calls the block once even when start eqals stop
fails:String#upto doesn't call block with self even if self is less than stop but stop length is less than self length
fails:String#upto doesn't call block if stop is less than self and stop length is less than self length
fails:String#upto doesn't call the block if self is greater than stop
fails:String#upto stops iterating as soon as the current value's character count gets higher than stop's
fails:String#upto returns self
fails:String#upto tries to convert other to string using to_str
fails:String#upto raises a TypeError if other can't be converted to a string
fails:String#upto does not work with symbols
fails:String#upto returns an enumerator when no block given
fails:String#upto returns non-alphabetic characters in the ASCII range for single letters
fails:String#upto stops before the last value if exclusive
fails:String#upto on sequence of numbers calls the block as Integer#upto
