Reverse a string or a number

Write a function reverseValue(value) that reverses a string or a whole number.

• value is a string or an integer from -1000000000 to 1000000000.
• For a string, return the string with its characters in reverse order: 'hello' gives 'olleh'.
• For a number, return a number with its digits in reverse order. The minus sign stays in front: -45 gives -54. Zeros at the start of the result drop: 1200 gives 21, and 0 gives 0.
• The result has the same type as value: a number gives a number, not a string. A string of digits is still a string: '120' gives '021'.
• The empty string gives ''.